Hello,
Although we can't provide you with real product keys to activate Windows 8.1 (they likely won't work anyway as Windows 8.1 has been out of support since January of 2023), we can provide you with a generic product key to install Windows. However, the generic key will only install Windows and not activate it. This will mean that many personalization features like wallpaper/lock screen customization and theme changing will be blocked.
For Windows 8.1 Home, use 334NH-RXG76-64THK-C7CKG-D3VPT, for Home Single Language, use Y9NXP-XT8MV-PT9TG-97CT3-9D6TC, for Pro, use XHQ8N-C3MCJ-RQXB6-WCHYG-C9WKB, and for Pro (with Media Center), use GBFNG-2X3TC-8R27F-RMKYB-JK7QT
For more information, you can go to https://www.eightforums.com/threads/clean-install-windows-8.2299/.
Hope this helps.