Microsoft Toolkit 2.6.2 Final is a functional, lightweight solution. Just ensure you download it safely.
This feature allows you to turn your local PC into a KMS host. This is useful for small offices with multiple computers that need to activate volume-licensed products without an official server. The toolkit installs a Windows service (KMS Server Service) that listens for activation requests from other machines on the local network. Microsoft Toolkit 2.6.2 Final -Windows