AutoCAD won't work on cloned drive. Workarounds?

[OctavioMasomenos]

I hope this isn't in violation of any forum rules, here. I'm working on a very old XP laptop for a client. He maintains it because there's an AutoCAD plugin that he really likes to use which is no longer available. (No longer being developed. I believe the developer died.) It won't run on newer versions of AutoCAD so he's using AutoCAD 2007. Obviously, he's worried about the drive or the system dying from old age. Plus it's awfully slow. So he hired me to try to create an XP virtual machine that he can run from within his new, fast system. But AutoCAD is, of course, very finicky; you don't have to change much for AutoCAD to say, "Sorry, you need to activate." To be extra cautious, I cloned his drive (I don't want to risk anything happening to the working drive) and put the clone in the machine - and just that caused AutoCAD to throw a license error.

Anyone know what it's looking for? The drive's serial number? UUID? Something else?