KMS vs MAK — how licensing really works
Two channels that look identical to the user but behave differently afterwards.
MAK keys carry a fixed activation count on Microsoft servers: each new machine consumes one, forever. KMS instead uses a local server that clients renew against automatically, which is exactly the channel activators emulate.
Why KMS renews without internet
Clients check the local KMS service on a schedule and refresh their activation from it. Once the local service is present, that renewal continues across reboots without contacting Microsoft at all.
Which channel do you have
slmgr /dli names the channel in its description. If it shows retail, no KMS tool will ever activate it without first converting to volume licensing.
How this affects real-world troubleshooting
Second-hand office PCs often ship with a KMS configuration pointing at the previous employer. Off that network, activation expires and the watermark returns even though Windows is genuine. Clearing the stale key and activating locally is the standard remedy, and understanding the difference stops people assuming the machine has a counterfeit licence.
Why volume clients keep a renewal timer
KMS clients check in periodically by design rather than storing an entitlement forever. On a personal computer using local activation, the local renewer performs exactly that role. Deleting it is what deactivates Windows after a while.
A simple rule for choosing keys
- A retail key suits one personal machine, subject to Microsoft's transfer rules after hardware changes.
- MAK suits a fixed number of machines without any local service.
- KMS suits ongoing activation without contacting Microsoft and behaves identically after every restart once the local service exists.