From what I know about life time subscription, you can't do that. The "lifetime" stays with the unit, so if it was a built in car unit... it stayed with the car and technically it can't be switched to a new owner (but how would they know right?).
If it was on a portable unit you can only set it up for that unit and move it anywhere. You might not be able to switch it to an in car unit.
Check it out first. I'd hate to see you drop $200 and then not be able to use the device.