How to Download, Install and Activate Office 2021 Professional Plus

You can install Office 2021 Pro Plus in about 30 minutes: download the official installer, run Setup, then activate with your product key. The process is not difficult, but it is easy to start in the wrong place. Microsoft no longer offers a simple download page for Office 2021 Professional Plus, and the right installer depends on which type of key you have: retail, phone activation, bind or LTSC volume.

Using the wrong installer is the most common reason activation fails. A retail key will not activate an LTSC volume installation, and a volume key will not activate a retail one, however many times you type it in.

There is also a timing point worth knowing. Office 2021 reaches end of support on October 13, 2026. Your installation will keep working after that date, but it will stop receiving security updates, which matters if you are choosing between Office 2021 and a newer version.

This guide explains how to download, install and activate Office 2021 Professional Plus for each key type, with practical checks and beginner-friendly explanations along the way.

How to Install Office 2021 Pro Plus: Quick Answer

The full process for most retail keys takes about 20 to 40 minutes:

1. Confirm which Office 2021 key type you bought: retail, phone, bind or LTSC.
2. Check that your PC runs Windows 10 or Windows 11.
3. Check whether Windows is 64-bit or 32-bit.
4. Uninstall any existing Office or Microsoft 365 apps, including trial versions.
5. Restart the PC.
6. Download the matching official installer from Microsoft.
7. Mount the image file or run the downloaded installer.
8. Run Setup and wait for installation to finish.
9. Open Word and enter your product key.
10. Activate online, or by phone with a Confirmation ID.
11. Confirm activation under File > Account.
12. Install the latest Office updates.

In simple terms:

Identify Key → Check PC → Remove Old Office → Download → Install → Activate → Verify → Update

Which Office 2021 Key Do You Have?

Every Office 2021 Pro Plus key installs the same apps: Word, Excel, PowerPoint, Outlook, Access and Publisher. What differs is how the license is delivered and activated.

Not sure which one you bought? Check the product name in your order email or under My Account. The product name tells you more than the key itself, which looks almost identical across types.

Office 2021 Pro Plus Compatibility by Windows Version

Office 2021 is a Windows product. The Mac version is a separate product with its own installer and keys.

Before You Install Office 2021 Pro Plus: Checklist

Ten minutes of preparation can save an afternoon of reinstalling. Check these points before downloading anything:

• Your PC runs Windows 10 or Windows 11
• You know whether Windows is 64-bit or 32-bit
• You have administrator rights on the PC
• You have at least 4 GB of free disk space, plus room for the installer file
• Your product key is saved somewhere you can copy it from
• Important files from any old Office installation are backed up
• You have a stable internet connection for the download

Microsoft’s minimum requirements for Office 2021 are a 1.6 GHz dual-core processor, 4 GB of RAM (2 GB for 32-bit), 4 GB of free disk space and a 1280 × 768 display. These are minimum specifications, not a promise of smooth performance, so 8 GB of RAM and an SSD give a noticeably better experience.

STOP: When you should not continue. Do not install Office 2021 Pro Plus alongside Microsoft 365 Apps on the same PC. Microsoft does not support that combination, and it is a common cause of activation and update errors. Remove Microsoft 365 first, or keep Microsoft 365 and skip this installation.

Step 1: Check Your Windows Version and Architecture

Office must match the system it runs on, so start by confirming what you have.

1. Open Settings > System > About.
2. Under Windows specifications, check the edition and version.
3. Under Device specifications, check System type.

If System type says 64-bit operating system, install 64-bit Office. Choose 32-bit Office only if you rely on an older add-in that does not support 64-bit.

Step 2: Uninstall Older Office Versions

Many new PCs ship with a Microsoft 365 trial or the Microsoft 365 app already installed. Leftovers from these, or from Office 2016 or 2019, can block setup or confuse activation.

1. Open Settings > Apps > Installed apps.
2. Search for Office and Microsoft 365.
3. Uninstall every Office suite, including trials and other language versions.
4. Restart the PC.

If an Office version refuses to uninstall, Microsoft provides an Office uninstall support tool that removes it completely. Run it, then restart before continuing.

IMPORTANT: Uninstalling Office does not delete your documents, but Outlook data stored locally in PST files should be backed up first. If Outlook is set up for work email, ask your administrator before removing it.

Step 3: Download Office 2021 Pro Plus

Download Office only from Microsoft or the Bcdkey Download Center. Modified or “pre-activated” installers from third-party sites are a common source of malware, and they often fail to activate with a genuine key anyway.

Option A: Retail Image (Retail, Phone and 5PC Keys)

Microsoft hosts an offline image of Office 2021 Professional Plus Retail on its own content delivery server, officecdn.microsoft.com. Every link below points directly to Microsoft, so no third-party download site is involved.

Choose the language you want Office to use. The table lists the most popular languages; for others, replace the language code in the link with your own, such as ja-JP or zh-CN. Each file is an offline copy of the Click-to-Run installer, between 4.3 GB and 4.9 GB, and it needs a retail key to activate.

Office 2021 Professional Plus Retail Download Links

Tip: You can add more languages later with Microsoft’s Office language packs, so pick the main language your PC uses. Links last checked: October 2026.

Option B: Bcdkey Download Center (LTSC Volume Keys)

Office LTSC Professional Plus 2021 uses volume licensing, so it needs the volume installer rather than the retail image above. Bcdkey provides ready-made LTSC installers in the Bcdkey Download Center, so there is no configuration file to write.

1. Open the Office 2021 LTSC download folder.
2. Open the folder for your language, such as EN (English), DE (German), FR (French), IT (Italian), ES (Spanish), NL (Dutch), PT (Portuguese), DA (Danish), FI (Finnish), NO (Norwegian) or SV (Swedish).
3. Download the file that matches your Windows, for example Office_2021_EN_64Bits.exe for 64-bit Windows or Office_2021_EN_32Bits.exe for 32-bit Windows.
4. Right-click the file and select Run as administrator.

The installer file is small, about 3.5 MB, because it downloads the Office files during setup. Keep the PC connected to the internet until installation finishes.

IMPORTANT: Some language folders also contain files with standard in the name. Those install Office LTSC Standard 2021, which a Pro Plus key will not activate, so choose the file without standard.

Option C: Microsoft Account (Bind Keys)

A bind key links Office to your Microsoft account, and the download then comes from that account.

1. Go to Microsoft’s Office setup page and sign in with the Microsoft account you want to use.
2. Enter your bind key and confirm your country and language.
3. Open your Microsoft account and select Services & subscriptions.
4. Find Office Professional Plus 2021 and select Install.

Use an account you plan to keep. Once the key is linked, the license stays with that Microsoft account.

Step 4: Install Office 2021 Pro Plus

For the retail image, Windows 10 and 11 can open the file without extra software:

1. Right-click ProPlus2021Retail.img and select Mount.
2. Open the new virtual drive in File Explorer.
3. Double-click Setup.exe and approve the administrator prompt.
4. Wait for the progress window to finish and show that Office is installed.
5. Right-click the virtual drive and select Eject.

Installation usually takes 10 to 20 minutes. The installer does not ask for your key, which surprises many people; activation comes next.

Can’t find the Office apps afterwards? See Office App Icon or Shortcut Is Missing.

Step 5: Activate Office 2021 Pro Plus Online

Online activation is the normal route for retail, 5PC and LTSC keys.

1. Open Word or any other Office app.
2. When the activation window appears, select I don’t want to sign in or create an account or Enter product key instead.
3. Type your 25-character key and select Activate.
4. Accept the license agreement.

If no prompt appears, go to File > Account > Change Product Key.

Activate Office 2021 With the Command Line

If the app window does not accept the key, the built-in OSPP script usually will. Open Command Prompt as administrator and run:

cd "C:Program FilesMicrosoft OfficeOffice16"
cscript ospp.vbs /inpkey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
cscript ospp.vbs /act

Replace the Xs with your key. Office 2021 still uses the internal version number 16, so the folder is named Office16. For 32-bit Office on 64-bit Windows, use C:Program Files (x86)Microsoft OfficeOffice16.

Step 6: Activate Office 2021 Pro Plus by Phone

Phone activation keys, and some retail keys on offline PCs, complete activation with a Confirmation ID instead of an online check.

1. Enter the key as shown in Step 5.
2. If Office reports that phone activation is required, run:

cd "C:Program FilesMicrosoft OfficeOffice16"
cscript ospp.vbs /dinstid

3. Copy the long Installation ID shown.
4. Generate your Confirmation ID with the Bcdkey Get Confirmation ID tool.
5. Apply it, replacing the Xs with your Confirmation ID and keeping your Activation ID from the previous output if requested:

cscript ospp.vbs /actcid:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
cscript ospp.vbs /act

Prefer clicking to typing? The activation wizard inside Office also offers I want to activate the software by telephone. Bcdkey’s guide on how to activate Microsoft Office by phone walks through both methods with screenshots.

Step 7: Verify Office 2021 Pro Plus Activation

Do not skip this step. A quick check now avoids a surprise “Product Notice” banner next week.

1. Open Word and go to File > Account.
2. Under Product Information, look for Product Activated and Microsoft Office Professional Plus 2021.

For a detailed check, run:

cscript ospp.vbs /dstatus

READY CHECK: The output should show LICENSE STATUS: ---LICENSED--- and a product name containing Office 2021. Anything else means activation is not complete.

Step 8: Install Office 2021 Updates

A fresh installation is often several months behind on updates. Install them straight away:

1. Open Word and go to File > Account.
2. Select Update Options > Update Now.
3. Close Office apps when asked and let the update finish.

Servicing updates do not need a new product key. Your existing activation carries over.

Does Office 2021 End of Support Mean It Will Stop Working?

No. Office 2021 reaches end of support on October 13, 2026, and Microsoft has said there will be no extension and no paid Extended Security Updates for it. End of support affects Microsoft’s servicing commitment rather than switching off the software.

After that date:

• New security vulnerabilities are no longer fixed
• Microsoft stops technical support for Office 2021
• Help content stops being updated
• Connections to newer Microsoft 365 services are no longer guaranteed

Your documents, activation and apps keep working. Office LTSC 2021 reaches the end of its support on the same date. Microsoft’s official end of support for Office 2021 page explains the details.

Should You Install Office 2021 or Office 2024?

It depends on how you use the PC. Office 2021 is not automatically the wrong choice, and Office 2024 is not automatically the better purchase simply because it is newer.

Office 2021 still makes sense when you:

• Already own an Office 2021 key and need to reinstall it
• Use an offline or isolated PC with limited internet exposure
• Need Publisher, which Office 2024 no longer includes
• Run older add-ins or templates validated only on Office 2021

Consider Office 2024 when you:

• Open email attachments and documents from outside your organization
• Want security updates for years rather than days
• Are buying a new license today
• Manage business PCs that must stay on supported software

Office 2024 is supported until October 9, 2029. For a one-time license, compare Office 2024 Professional Plus LTSC, which activates online on one Windows PC, and the Office 2024 Pro Plus LTSC Phone Activation key for offline PCs. Neither works on macOS, and neither is a key upgrade for an existing Office 2021 installation, so you install Office 2024 fresh.

Common Office 2021 Installation and Activation Mistakes

1. Installing the Wrong Edition

A Pro Plus key only activates Professional Plus, so installing Home and Business or Standard first means the key will be rejected.

2. Mixing Retail and Volume Installers

Retail keys need the ProPlus2021Retail image and LTSC keys need the LTSC installer from the Bcdkey Download Center, so match the installer to the key type in the table above.

3. Leaving Microsoft 365 Installed

A preinstalled Microsoft 365 trial can take over activation, so uninstall it before setting up Office 2021.

4. Using a Pre-Activated Download

Modified installers can carry malware and block genuine activation, so download only from Microsoft.

5. Copying the Installation ID Incorrectly

One wrong digit produces an invalid Confirmation ID, so copy the Installation ID in groups and check it twice.

6. Using a 5PC Key Beyond Five Devices

Each activation counts toward the limit, so record which PCs use the key.

Office 2021 Pro Plus Installation Checklist

Before Installation

Installation

Activation and Updates

Final Recommendation

To install Office 2021 Pro Plus successfully, the download matters less than you might think. It is about matching the installer to your key type, because that single choice decides whether activation succeeds on the first try.

For a retail, phone or 5PC key, use the official ProPlus2021Retail image. For an LTSC key, use the LTSC installer from the Bcdkey Download Center, and for a bind key, install from your Microsoft account.

Remember that Office 2021 reaches end of support on October 13, 2026. If you already own a key, it is still a working, practical option, especially on offline PCs. If you are buying a new license for a PC that handles email and outside documents every day, Office 2024 is the longer-term choice.

One concrete tip: write down which PC each key is activated on. It makes future reinstalls and support requests much faster.

If activation does not complete, open a support ticket with your order number and a screenshot of the error. When you are ready to choose an edition, compare the full Microsoft Office range on Bcdkey.

FAQ About How to Download, Install and Activate Office 2021 Professional Plus

Where can I download Office 2021 Professional Plus?

Download it from Microsoft’s own servers. Retail keys use the ProPlus2021Retail image on officecdn.microsoft.com, LTSC keys use the installer from the Bcdkey Download Center, and bind keys install from your Microsoft account.

Does the Office 2021 installer ask for a product key?

No. Setup installs Office without a key, and you enter the key the first time you open an Office app or under File > Account.

Can I use a retail key with Office LTSC 2021?

No. Retail keys activate only the retail installation, and LTSC volume keys activate only the volume installation from the LTSC installer.

How do I activate Office 2021 without internet?

Use phone activation. Run cscript ospp.vbs /dinstid to get your Installation ID, generate a Confirmation ID with the Bcdkey Get Confirmation ID tool, then apply it with /actcid.

Will Office 2021 stop working after October 13, 2026?

No. Office 2021 keeps working after end of support, but Microsoft stops releasing security updates and technical support for it.

Can I install Office 2021 and Microsoft 365 on the same PC?

No. Microsoft does not support running Office 2021 and Microsoft 365 Apps together, so remove one before installing the other.

Does Office 2021 Pro Plus work on Mac?

No. Office 2021 Professional Plus is for Windows only; Mac users need Office 2021 for Mac, which is a separate product and key.

Do I need a new key after reinstalling Windows?

Normally, no. You can reinstall Office on the same PC with the same key, although a major hardware change may require phone activation.

Is Office 2024 an upgrade for an Office 2021 key?

No. Office 2024 needs its own key and a fresh installation; an Office 2021 key does not activate Office 2024.