Windows 7 Premium edition can be upgraded to Windows 7 Ultimate or Windows 7 Professional editions only. One can use WAU for upgrading his current upgrading system. Windows Anytime Upgrade (WAU) for Windows 7 is a Microsoft utility used for upgrading Windows 7 versions by buying a license online. Users can easily upgrade Windows 7 versions by using this utility. The WindowsAnytimeUpgrade.exe file is stored in the %SystemRoot%\System32 folder. Users can start upgrade by selecting Windows Anytime Upgrade on the Start menu and then following the prompts. Windows 7 will be available in six different editions, but only Home Premium and Professional will be available for retail sale in most countries. The other editions are focused at other markets, such as the developing world or for enterprise use.