In Windows 8 Microsoft have made it a little more difficult to activate a clean install of the Windows 8 Professional Upgrade than it was with Windows 7.
This is how it’s done:
- Run the registry editor by typing ‘regedit‘ on the start screen
- Find the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\OOBE
- Change the value for ‘MediaBootInstall’ from 1 to 0
- Open an elevated command prompt by typing ‘cmd‘ at start screen and right clicking, then choosing ‘Run as Administrator‘ at the bottom
- Run the following command: slmgr -rearm
Disclaimer: I can’t be held responsible for any problems that might arise from following this guide.