I may not be reading correctly but.... it says this is NOT transferable to another BlackBerry device. Now I don't know if they will allow you to change your PIN if you upgrade your device, but at first glance it would appear not.
"Garmin Mobile for BlackBerry’s $99.99 one-time purchase is available directly from Garmin at Garmin | Garmin Mobile
. The one-time purchase plan for Garmin Mobile for BlackBerry is not transferable between BlackBerry devices."