I own other software that is only licensed to be installed and run on a single machine, but the software company gives me a web page where I can disconnect a given license key from a given MAC Address and, once having done so, register it for use on a different computer. Parallels should do that. Instead we have to go begging for an intervention by a Parallels tech if the computer on which we were previously using Parallels Desktop dies. Parallels instructions say to go to the old machine and log out. That's fine if the old machine is just being retired. It's less fine if the old machine just fried its motherboard.