The method used to activate Windows for single-user licenses starting with Windows XP and Windows Server 2003. Bulk licenses to companies do not contain Windows Product Activation (WPA).

Usually, you'd activate Windows 11 (or 10) using the Settings app to enter the product key. However, if you're in an enterprise environment and you have a specific type of activation key ...

z4 sued the two companies in 2004, saying that Microsoft used its patented product activation technologies to prevent casual copying of Microsoft's Office and Windows XP, and Autodesk's AutoCAD.