If he registered it to unlock the maps online, Garmin recorded his units serial number. I dont think you would be able to use his software then. When I upgraded my Garmin software, they seemed to have specific software for multiple units, not just for one specific. Go to their website (Garmin.com) and click on "Maps & Charts". Then "On the Road" or whatever link applies to you. On the right of this page will be a Map viewer and a MapSource Compatibility tool. Put in the unit your looking to buy and see what it costs.