The "Microsoft Office LTSC Professional Plus 2021 Preview has expired" message occurs because the preview version is a temporary license that has reached its end-of-life. To fix this, you must replace the preview license with a permanent one or install a supported version of Office. Step 1: Remove the Expired License
Activate the Final Version: Finally, Alex opened Word again. This time, instead of an expiration warning, they were prompted to sign in with a Microsoft account or enter a genuine product key. A New Chapter
Before installing a new version, it is critical to perform a "clean" uninstall to prevent license conflicts. Standard Uninstall : Navigate to Settings > Apps > Apps & Features , find the preview version, and select Deep Clean : For persistent issues, use the Microsoft Support and Recovery Assistant (SaRA)
For individual users: Contact Microsoft Support via chat or phone. If you purchased a genuine key but the preview is blocking it, support agents can run a remote tool to flush expired licenses.
If you have a legitimate license key for the final version of Office LTSC 2021, you should uninstall the preview and install the official version.