While the service was officially discontinued by Microsoft on October 31, 2015, understanding how these keys worked is still relevant for users maintaining legacy systems or those looking for modern alternatives. What is a Windows Anytime Upgrade Key?
A Windows Anytime Upgrade (WAU) key was a 25-character product key that unlocked additional features already pre-installed on your computer. Because all editions of Windows 7 (from Starter to Ultimate) shared the same underlying installation files, entering this key simply "switched on" the premium features associated with higher-tier editions. Common upgrade paths included: to Windows 7 Home Premium Windows 7 Home Premium to Windows 7 Professional Windows 7 Home Premium to Windows 7 Ultimate How to Use an Anytime Upgrade Key anytime upgrade key