Key Management Service (KMS) and Multiple Activation Keys (MAK) are volume licenses meant for businesses, schools, and organizations. When these keys leak online, thousands of people try to use them. Microsoft quickly detects this abnormal activity and blocks the key permanently. 3. Fake or Generated Keys
Leo went home and tried it. He opened the Activation settings on his 64-bit build and typed in the 25-character code from the fading sticker. For a moment, the circle spun. Then, like magic, the "Activate Windows" watermark vanished. The old Windows 7 key had been recognized by Microsoft’s servers as a valid entitlement for a free upgrade.