For a long time I was annoyed by that watermark. Every KMS tool I tried gave me 185 days, then the "Activate Windows" message came back. I wanted to patch it to be permanent. Then I actually understood how it works. 1. What KMS really is? KMS = Key Management Service. It's not a crack originally. It's an official Microsoft system for large companies. Instead of activating 5000 PCs one by one, they install one local KMS server. All PCs activate against it. 2. Why exactly 180/185 days? It's by design. It's a lease. A KMS license must renew every 180 days to prove the PC is still part of the company. If it can't reach the server, it deactivates. The extra 5 days (185 total) is just a grace period. You see it when you run slmgr /dlv. So any tool giving you 185 days is just emulating a fake KMS server. It's not broken, it's doing exactly what Microsoft designed. 3. The watermark is annoying but not blocking Unlike old Windows, Windows 10/11 unactivated is 99% usable. Microsoft only blocks: Personalization (wallpaper, colors) Some settings Security updates, your IDE, browsers, everything still works. 4. What I do now as a dev (legal options) Stay unactivated for test machines: It's allowed and free. Get a cheap legit OEM key: $15-$25 on official Microsoft resellers. Permanent and tied to your motherboard. For devs: Microsoft offers free 90-day Windows VMs at developer.microsoft.com - perfect for testing. Final thought Trying to modify KMS source to make it permanent crosses into illegal reverse-engineering. Understanding why it expires helped me stop fighting it. I now use unactivated Windows for my VMs and a legit key for my main machine. No more watermark stress. windows, licensing, devtools, microsoft