When you activate Office, you might receive an error message that your product key has been blocked.
If your Office product key doesn’t work, or has stopped working, you should contact the seller and request a refund. If you bought a product key separate from the software, it’s very possible the product key was stolen or otherwise fraudulently obtained, and subsequently blocked for use. Unfortunately, there are many dishonest sellers who offer stolen, abused, or otherwise unauthorized Microsoft product keys for sale. Sometimes these product keys are printed on counterfeit labels or cards with a download link to Microsoft software, and sometimes they’re distributed with software media that is unauthorized for resale, such as promotional media, original equipment manufacturer reinstallation media, or other Microsoft program-specific media.
If you can't get a refund from the seller and still need Office, you can buy the latest version of Office from Microsoft.