Windows 11 Forum:
The number of Windows 10 licensing and activation questions around the tech forums started to grow exponentially when Windows 7 hit its End of Life date. Users keep asking about how to find their Windows 10 or 11 product key after upgrading from Windows 7. The short answer is, there’s no need to find the key. That’s because Windows 10 and 11 are digitally licensed once a specific edition gets activated for the first time. All future clean installs on same machine will be automatically activated based on that existing, edition-specific digital license.
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Digital License is based on the host PC’s so-called hardware ID. The Digital License is stored on Microsoft’s activation servers, and when Windows 10 or 11 will be installed and it gets an Internet connection, the license status will be checked.
Important to know, is that Windows 10 and 11 licences are intertwined. A Windows 10 licence activates a Windows 11, too, and vice versa.