Follow these steps to install Office and activate it with your product key.
Step 1: Remove old or trial versions
Open Control Panel → Programs → Uninstall a program and remove any other Office or Microsoft 365 trial. Mixed versions are the #1 cause of activation errors.
Step 2: Download the installer
- Home & Student / Home & Business keys: go to setup.office.com, sign in with your Microsoft account, enter the key, then download Office from your account page.
- Professional Plus keys: use Microsoft's official Office Deployment Tool. The download link is on the product's Download tab and in your KeyForPC account under Downloads.
Step 3: Activate
- Open Word or Excel.
- Go to File → Account → Change Product Key (or use the activation prompt).
- Paste your 25-character key and click Activate Office.
- Restart the app. The Account page should say Product Activated.
Common problems
- "This product key isn't for this version" — the installed version (e.g. 2019) doesn't match your key (e.g. 2021). Install the matching version.
- Office keeps asking to sign in — you may have a Microsoft 365 trial installed; uninstall it.
- Still stuck? Open a support ticket with a screenshot — help is free.
Need a key? Browse Microsoft Office keys →