This method is legal. You can read these articles to know :
- https://docs.microsoft.com/en-us/windows-server/get-started/kmsclientkeys
- https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-R2-and-2012/dn502531(v=ws.11)
Step 1: You visit bit.ly/windows10txt
Step 2: You copy the code above into a new text document
Step 3: You save it as a batch file , name “windows10.cmd”
Note : IF you use windows 10, you save it as .bat (named “windows10.bat”)
Step 4: You run the batch file as administrator
You can see the result
Update 09-10-2019: Now Microsoft doesn’t allow to use batch file so Windows Defender detects my scripts as “HackTool:BAT/AutoKMS”. Somebody sent email to me to describe their problem:”When I opened it as admin, the command center just popped up then disappar”. So you need to disable Windows Defender or you can try method 2 of below.
You can watch this video to know How to activate windows 10 without product key for free 2019
