1. open regedit
2. search this: HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE
3. Change "MediaBootInstall" from "1" to "0"
4. open cmd with admin privilegies
5. tipe this: slmgr /rearm and hit enter
5. restart pc/laptop etc.
6. again open cmd with admin privilegies
7. then install your key with these commands:
7a. slmgr /ipk XXXX-XXXX-XXXX-XXXX and hit enter
7b. slmgr /ato and hit enter.