Microsoft Office 2021 Professional Plus: How to Download, Install & Activate (2026 Guide)

Microsoft Office 2021 Professional Plus is one of the most popular productivity suites in the world — and for good reason. It's the perfect balance of modern features, classic reliability, and one-time-purchase ownership. In this comprehensive DotKeys guide, you'll learn how to download, install, and activate Office 2021 Pro Plus on your Windows PC in just a few simple steps.

What's in Office 2021 Professional Plus?

Office 2021 Pro Plus includes every app you need to work, create, and collaborate:

• Microsoft Word 2021 – word processing with co-authoring
• Microsoft Excel 2021 – spreadsheets with XLOOKUP, LET, LAMBDA functions
• Microsoft PowerPoint 2021 – modern presentations with recording studio
• Microsoft Outlook 2021 – email and calendar
• Microsoft OneNote 2021 – digital notebook
• Microsoft Access 2021 – database creation and management
• Microsoft Publisher 2021 – desktop publishing

All apps include the 2021 visual refresh, performance improvements, and better collaboration features.

💡 DotKeys Tip: Office 2021 Pro Plus is a perpetual license — buy it once, own it forever. No monthly or yearly fees.

Office 2021 Pro Plus System Requirements

Pre-Installation Checklist

Before you start:

✅ Uninstall previous Office versions — go to Control Panel → Programs → Uninstall a program. Reboot afterwards.

✅ Disable antivirus temporarily during install (re-enable after).

✅ Have your Office 2021 product key ready from your DotKeys confirmation email.

Part 1: How to Download Office 2021 Professional Plus

Microsoft hosts Office 2021 Pro Plus as an ISO image on their official CDN. Here's how to get it.

Official Download Link

Use the direct Microsoft download link:

👉 https://officecdn.microsoft.com/db/492350f6-3a01-4f97-b9c0-c7c6ddf67d60/media/en-us/ProPlus2021Retail.img

Step 1: Open your browser and paste the link above. The file is approximately 4–5 GB, so make sure you have a stable internet connection.

Step 2: Once downloaded, locate the .img file in your Downloads folder.

Step 3: Double-click the .img file to mount it as a virtual DVD drive. On Windows 10/11, this is built-in — no extra software needed.

Step 4: The mounted drive will appear in File Explorer under "This PC."

💡 If mounting fails: Right-click the file → Open with → Windows Explorer, or use a free tool like 7-Zip or WinRAR to extract it.

Part 2: How to Install Office 2021 Pro Plus

Step 1: Open the mounted virtual drive in File Explorer.

Step 2: Find the Setup.exe file.

Step 3: Right-click Setup.exe and select "Run as administrator".

Step 4: If Windows asks "Do you want to allow this app to make changes to your device?", click Yes.

Step 5: The Office 2021 installation wizard will open. Wait for it to download and install all components. This usually takes 5–15 minutes depending on your internet speed.

Step 6: When you see "You're all set! Office is installed now", click Close.

🎉 That's it! Office 2021 Pro Plus is now installed on your computer.

Part 3: How to Activate Office 2021 Pro Plus

Now let's activate your license.

Activate with Your Product Key

Step 1: Open any Office app (Word is the easiest). Press the Start button, type Word, and click the app.

Step 2: When the sign-in prompt appears, click "I don't want to sign in or create an account" at the bottom.

Step 3: Click "Enter a product key instead".

Step 4: Enter your 25-character Office 2021 product key from DotKeys (format: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX).

Step 5: Click Install (or Activate Product).

Step 6: Wait a few seconds for Microsoft to verify the key. The screen will confirm activation.

Step 7: Close and reopen the Office app to finalize activation.

Verify Your Activation

Step 1: Open any Office app.

Step 2: Click File → Account (bottom-left corner).

Step 3: Check the "Product Information" section. It should say "Product Activated" with a green checkmark.

Alternative: Phone Activation

If online activation doesn't work (rare, but possible due to network restrictions), you can activate by phone:

Step 1: Open any Office app → File → Account → Activate Product.

Step 2: Choose "Activate by phone".

Step 3: Select your country and dial the free number.

Step 4: Follow the voice prompts and enter the installation ID when asked.

Step 5: You'll receive a confirmation ID — type it back into the boxes on screen.

Step 6: Click Next, then Finish.

Troubleshooting Common Problems

Why Buy Office 2021 Pro Plus from DotKeys?

Don't pay Microsoft's $439.99 retail price. At DotKeys, you get:

• ✅ 100% genuine Microsoft license keys — verified and tested
• ⚡ Instant delivery — your key arrives in your inbox within minutes
• 💰 Up to 80% off MSRP — the same software at a fraction of the price
• 🔄 Lifetime activation — no subscription or renewal
• 🛠️ 24/7 customer support — we're here whenever you need help
• 🔒 Secure SSL checkout — your data is protected
• 💵 Money-back guarantee — if it doesn't activate, you get a full refund

👉 Buy Office 2021 Professional Plus from DotKeys →

Frequently Asked Questions (FAQ)

What's the difference between Office 2021 and Office 365?

Office 2021 is a one-time purchase — you pay once and own it forever. Office 365 (Microsoft 365) is a subscription service that includes OneDrive cloud storage, Teams, and continuous feature updates. Choose Office 2021 if you prefer a one-time payment and don't need cloud features.

Does Office 2021 work on Windows 11?

Yes. Office 2021 Pro Plus is fully compatible with Windows 10 and Windows 11.

Can I install Office 2021 on a Mac?

No. Office 2021 Pro Plus is a Windows-only license. For Mac, you need Office for Mac 2021 (sold separately). We recommend Office 365 for Mac if you need cross-platform support.

Can I transfer my Office 2021 license to a new PC?

Yes! Office 2021 Pro Plus is a retail license — you can transfer it to a new PC by simply uninstalling it from the old one and installing on the new one using the same product key. Just make sure to remove it from the old device first.

How long does Microsoft support Office 2021?

Microsoft supports Office 2021 Pro Plus with security updates until October 2026. After that, you'll need to upgrade to a newer version.

Will my Office 2016 or 2019 product key activate Office 2021?

No. Each Office version requires its own dedicated product key. Buy a separate Office 2021 Pro Plus key from DotKeys to activate this version.

Does Office 2021 include Access and Publisher?

Yes! Access and Publisher are included in Office 2021 Professional Plus (not in Home & Business or Home & Student). The Pro Plus edition is the only one that gives you the full suite.

What if my key from DotKeys doesn't activate?

Just contact our 24/7 support team through live chat. We'll provide a working replacement key or issue a full refund — hassle-free.

Final Thoughts

Microsoft Office 2021 Professional Plus remains one of the best productivity investments you can make. With Word, Excel, PowerPoint, Outlook, OneNote, Access, and Publisher — all activated with a single, perpetual license — it's the productivity suite that pays for itself.

Skip the Microsoft Store markup and get your genuine Office 2021 Pro Plus key from DotKeys for instant delivery, lifetime activation, and unbeatable support.

Time to get to work! 💼

Related guides:

• Office 2024 Pro Plus Setup Guide →
• Office 2019 Pro Plus Setup Guide →
• Office 2016 Pro Plus Setup Guide →
• Microsoft Project 2021 Pro Setup Guide →

Last updated: January 15, 2026 — by the DotKeys Team