Yes, even though the free upgrade period expired some time ago Microsoft haven’t bothered to officially end it.
The upgrade should not ask for a key or any machine ID.
I would recommend imaging the drive before upgrading in case of problems.
You can also see if there’s a Win 7 key in the BIOS & make a note of it:
Run this cmd within powershell with admin powershell “(Get-WmiObject -query ‘select * from SoftwareLicensingService’).OA3xOriginalProductKey”
Or wmic path softwarelicensingservice get OA3xOriginalProductKey if using cmd prompt.
Or: Check this program to reveal if there’s a key embedded in the BIOS:
neosmart.net
Or: Download and run this:
https://www.microsoft.com/en-us/p/showkeyplus/9pkvzcprx9nv to find all keys used on the PC.