In short: Download the official Office 2021 Professional Plus disk image from Microsoft, mount it, run Setup, then open Word or Excel and enter your 25-character product key when asked. Office 2021 Pro Plus includes Word, Excel, PowerPoint, Outlook, OneNote, Access, Publisher and Teams.
Before you start
Check that your PC meets the Office 2021 Professional Plus system requirements:
| Operating system | Windows 10 or Windows 11 |
|---|---|
| Processor | 1.6 GHz or faster, 2 cores |
| RAM | 4 GB (64-bit), 2 GB (32-bit) |
| Storage | 4 GB of free disk space |
| Graphics | DirectX 10 or later for hardware acceleration |
| Display | 1280 x 768 or higher |
| You will also need | An internet connection and your Office 2021 Pro Plus product key |
Remove older Office versions first. Uninstall any existing Office or Microsoft 365 apps in Settings > Apps before you install. Mixed versions are the most common cause of installation and activation errors.
Step 1: Download Office 2021 Professional Plus
- Download the official Office 2021 Professional Plus disk image (English) from Microsoft's servers. The file is named
ProPlus2021Retail.img. - Wait for the download to finish. The file is several gigabytes.
Step 2: Install Office
- Open your Downloads folder, right-click
ProPlus2021Retail.imgand select Mount. Windows opens the image as a new drive. - Double-click Setup and click Yes if User Account Control asks for permission.
- Wait while Office installs. This usually takes 5 to 15 minutes, depending on your connection.
- Click Close when the installer says Office is ready.
Step 3: Activate Office 2021 Professional Plus
- Connect the PC to the internet and open Word or Excel.
- When the activation window appears, enter the 25-character key from your Msckey order email. If it doesn't appear, go to File > Account and click Change Product Key or Activate Product.
- Click Activate Office and follow the prompts.
- Check File > Account. It should show Product Activated, Microsoft Office Professional Plus 2021.
Bought the 5-PC edition? Your Office 2021 Pro Plus 5 PC key activates up to five computers. Repeat steps 1 to 3 on each PC using the same key.
If activation fails
- "This product key can't be used": make sure no other Office version is installed, then restart the PC and try again.
- Phone activation keys: in the activation window, choose I want to activate the software by telephone, select your country, and use the Installation ID on our Get Confirmation ID page.
- Still stuck? Email support@msckey.com with your order number and a screenshot of the error.
Need an Office 2021 Pro Plus key?
Msckey sells genuine Office 2021 Professional Plus keys with a one-time payment, delivered by email, usually within 1 to 24 hours of payment confirmation.
My Wishlist
Wishlist is empty.