How to Activate Windows 10 with CMD Without a Product Key Activating Windows 10 usually requires a 25-character digital license or product key. However, if you are in a pinch—perhaps you've reinstalled Windows and can’t find your documentation—you can use the to activate your system using KMS (Key Management Service) client keys provided by Microsoft.
Type the following command and press Enter (replace XXXXX-XXXXX-XXXXX-XXXXX-XXXXX with your generic key):
