So I've had a look around but can't find a clear answer for my question. I performed a clean install of Windows 8 using the ISO that came from MSDN (en_windows_8_x64_dvd_915440.iso) and used an activation server to activate it until Febuary. Can I use the $15 upgrade offer to make my current installed version of Windows 8 fully activated or will I have to reinstall Windows 7 and install Windows 8 again?