On January 8th, 2019, Windows 7 machines that were activated through Key Management Service started receiving a “Windows is not genuine” error indicating that the license is not valid. It turns out this this problem was not related to a January Patch Tuesday update, but rather caused by a problem on Microsoft’s activation server. […]

from https://www.bleepingcomputer.com/news/microsoft/windows-7-kms-activation-issues-caused-by-microsoft-mistake-not-an-update/