https://learn.microsoft.com/en-us/windows-server/get-started/kms-client-activation-keys?tabs=server2025%2Cwindows1110ltsc%2Cversion1803%2Cwindows81
Key Management Services (KMS) client activation and product keys | Microsoft Learn
Find the Generic Volume License Keys (GVLKs) required to activate Windows and Windows Server editions using a Key Management Services (KMS) host.
key management servicesproduct keyskmsclient