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

Office 2021 Professional Plus logo on an abstract orange background. How to Download, Install, and Activate Office 2021 Professional Plus for Windows

This guide walks you through how to install Office 2021 Professional Plus, including how to download and activate it. Activation is done through a one-time key.

✅ Before You Begin

  • You’ll need a Windows PC

  • Internet connection is required for activation

  • Your license key is valid for one-time use only

⚠️ Important:

One key can be used only one time for one activation on one installation.
Once activated, Office 2021 Pro Plus is licensed for lifetime use on that installation.
If you need to reinstall in the future on the same or a new machine, you’ll need to purchase a new key.

💻 Installation on Windows

1. Download the installation file

You can also install additional languages later by going to:
File → Options → Language → Add a Language

🌐 Other Available Languages

2. Mount the image file

  • Locate the .img file you downloaded

  • Double-click it to mount it as a virtual CD

  • If it doesn’t open automatically:

    • Open File Explorer

    • Go to This PC

    • Look for the new virtual CD/DVD drive and open it

🛠️ Other Ways to Mount a .img File in Windows

  • ✅ Option 1: Use the Right-Click Menu

  1. Right-click the .img file

  2. Choose “Mount” from the context menu

If “Mount” isn’t listed, try Option 2 or 3 below.

  • ✅ Option 2: Use File Explorer’s Ribbon Menu

  1. Select the .img file

  2. At the top of File Explorer, go to the Manage / Disk Image Tools tab

  3. Click Mount

  • ✅ Option 3: Use Windows PowerShell

  1. Right-click Start and open Windows PowerShell (Admin)

  2. Run this command:

Mount-DiskImage -ImagePath "C:\Path\To\Your\File.img"

Replace the path with the actual location of your .img file.

  • ✅ Option 4: Use Third-Party Software (if needed)

If none of the above work, you can use free tools like:

These tools create a virtual drive and automatically mount the .img file when opened.

3. Install Office 2021 Professional Plus

  • Run Setup.exe from the mounted virtual drive

  • The installation will start automatically

  • Wait for it to finish (no Microsoft account required)

4. Activate Office 2021 Pro Plus

  • Open any Office app (e.g., Word or Excel)

  • Go to File → Account → Activate Product

  • Choose “I have a product key”

  • Enter your 25-character activation key

  • Click Activate

✅ If successful, your product will display:
“Product Activated”

🧠 Troubleshooting Tips

  • Double-check for typos when entering the key

  • Ensure your internet connection is stable

  • If the setup file doesn’t run, try running it as administrator

  • Still having trouble? Contact our support below

🤝 We’re Here to Help

✅ Ready to Get Started?

If you don’t yet have your key, get a genuine Office 2021 Professional Plus license now:

🎯 Instant delivery, secure activation, and expert support included.
👉 Buy Office 2021 Professional Plus from Top Key Shop