Same damn problem here. Old Mac: dead as a doornail. Replacement Mac: same hard drive (just moved it over). Parallels 13 says "license already in use". Instructions in useless help center say "Go to old Mac and log out". Yeah right. Nobody is ever again going to log in, out, or sideways on that machine. It is fried to a crackly crunch. How do I disassociate my installation / reg key from the now-dead old Mac so I can register it on the replacement Mac?