I originally had some trouble getting my key to activate when trying to upgrade Windows 11 Home to Windows 11 Pro. What you need to do is open an admin command prompt and type slmgr /upk. Then you need to type slmgr /cpky to remove the key from the registry. Next, you need to type slmgr /rearm and restart the system. Now, put in a generic Windows 11 Pro activation key from https://docs.microsoft.com/en-us/windows-server/get-started/kms-client-activation-keys. Type the key into the activation box. It might throw up an activation error, but just restart the system and you should be on an unactivated copy of Windows 11 Pro. Now, go to your settings and change your product key to the key that you just purchased from here and it should work with no problems.

Clean install of Win 11 Home on new 12900k. Entered Code, asked if I was ready to upgrade my Windows version. I selected continue. Took a minute to install a couple updates. Finished, said that it could not activate and to try again later. I then Selected Troubleshooting option, at which point the license immediately activated. Thanks!

Got key instantly and had no issues activating windows. Will use again.

Perfekt, am anfang gab es nur ein kleines problem, dass Windows meinte das der Code jetzt nicht benutzt werden konnte....das ist aber komplett falsch. Der code hat funktioniert, nur der code den ich schon zuvor im System hatte war noch aktiv und hat sich im endeffekt gegenseitig . lösung: eingabeaufforderung als admin starten und slmgr -upk eingeben, danach pc neustarten und zack wird mit dem neustart gleichzeitig das update begonnen....fertig

SI, SI!!! ya se... al fin un comentario en español.
Solo diré, compra a ojos cerrados, a veces encontrar estas cosas es muy desconfiado por semejantes precios tan baratos, pero este es uno de esos productos con los cuales no tienes problemas.
De acá compré licencia Retail Windows 10 y ahora... mi licencia windows 11 pro