I wanted to reset a rather old Windows 10 computer, so used the Windows 10 reset option. This resulted in an endless boot loop, and while trying to fix this I found a backup and restore method from Dell. I tried that, it worked, but it turns out that the computer is now back to Windows 7 Professional. My guess is that it was a free update to Windows 10.
NB: I don't have the W7 key, and the sticker on the side is unreadable.
Is is possible to do another upgrade to Windows 10? Can I prove somehow that this computer had an update before? Will an upgrade or fresh W10 install destroy the recovery partition from Dell?