If you need to recover a serial number from a currently
working version of Auto CAD, prior to a wipe for example, it can be located in
the following or similar registry location for version 2010 onwards.
HKLMSOFTWAREAutodeskAutoCADR17.2ACAD-7001:409
The key youre looking for will definitely have the :409 at
the end and the string is listed as SerialNumber