Windows 10 to 11 free upgrade offer - how would one 'prove' the upgrade took place during the offer period?

Question

I know that Microsoft has not, as of yet, specified an end date for the free upgrade from Windows 10 to Windows 11.

I have a few business machines that originally had Windows 10 Pro Retail installed (with ESD keys bought from a legitimate Microsoft Partner). Some of those machines have already been upgraded to Windows 11 Pro.

My question is, should the free upgrade offer come to an end, how can one prove to Microsoft, during an audit further down the line, that these machines were indeed upgraded while the free upgrade offer was still active?

AFAIK, the same question hovered during the W7 to W10 transition period, while the offer was running (until July 2016). While Windows 10 still activates fine with W7 keys to this day, these post-2016 licenses are apparently technically not valid.

Is there a way to keep 'proof' of some sort for the future, that these W11 upgrades were indeed legitimate?

Answer 1

Windows 7 and 8.1 can still be upgraded to Windows 10 for free.

Once a computer has been upgraded licensing data is on Microsoft servers.

This enables a clean install, drive replacement, and major hardware replacement.

https://support.microsoft.com/en-us/windows/using-the-windows-activation-troubleshooter-d717cdff-cf19-9770-7198-40119c2a696c

https://support.microsoft.com/en-us/windows/reactivating-windows-after-a-hardware-change-2c0e962a-f04c-145b-6ead-fb3fc72b6665

If you want to record product keys then run:

Showkey
https://www.tenforums.com/windows-updates-activation/69647-activation-troubleshooting.html

or

Belarc Advisor
https://www.belarc.com/products/belarc-advisor

Command line to view the original product key:
wmic path softwarelicensingservice get OA3xOriginalProductKey

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Answer 2

I'd suggest hanging on to the original documentation as proof.

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