Is there a hidden reg or file that holds the serial # for recovery NU16

Have a problem with a cpu am working on that the owner has lost his serial # and 1 he has will not work not sure why as it is a 16 key but comes up as expired. 1 lost is not and NU16 is not on his product page. Does not know where downloaded it from either. Program has started having some issues, mainly it no longer runs at scheduled start up time for cleaning. Manually it works fine. Have tried a few tricks to get it to take a time and date but nope.

So is there a registry key or hidden file holding the serial # so that it would be possible to reinstall it again ? Or is there a trick have not tried to get NU16 to run on schedule ? This trick would prob have to be not in the Gui interface. Thanks