Activate Windows 8 Pro Upgrade

Activate Windows 8 Pro Upgrade

Windows 8 users who noticed that the operating system can’t be activated after the installation may want to try the following workaround that worked to activate when installing Windows 8 using an upgrade on a clean PC.

• Open regedit by pressing Windows-q, entering regedit and selecting the result from the list of hits.
• Navigate to HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/
• Change MediaBootInstall from 1 to 0
• Go back to the start screen and enter cmd there.
• Right-click Command Prompt and select to run it as administrator.
• Type slmgr /rearm on the command line and hit enter.
• Reboot Windows now.
• Run the activation utility afterwards, enter your product key to activate Windows.

Source: http://www.ghacks.net/2012/10/27/windows-8-upgrade-clean-install-possible/