KMSoffline and similar tools are designed to activate Microsoft Windows and Office products. They do this by generating a KMS activation key or by emulating a KMS server that the Windows or Office product can then use to validate and activate.
KMSoffline creates a "fake" server on your local machine. When Windows or Office checks in to see if it’s legal, the tool sends back a spoofed "Yes". The 180-Day Cycle: KMSoffline v2.4.1 -Windows Office Activator- ...