I'm not deep enough in this yet to know the cost, but here is the poop on the transfer etc.
If you purchased your Lifetime subscription
Before June 20, 2005: Yes, it is transferable from one radio to another any number of times.*
From June 20, 2005 until September 7, 2007: Yes, your Lifetime subscription is transferable a maximum of three times.*
On or after September 8, 2007: Lifetime subscriptions associated with home, portable or dock & play radios can be transferred a maximum of three times.* Lifetime subscriptions first associated with or transferred to radios installed in vehicles by automakers or dealers are NOT transferable unless the radio is stolen, accidentally damaged or defective.
Once a lifetime subscription associated with a home, portable, or dock & play radio is transferred to a radio installed by an automaker or dealer, the subscription becomes non-transferable. Otherwise, Lifetime subscriptions associated with a home, portable or dock & play radio can be transferred a maximum of three times, for a fee.*
Please call 1-866-635-2349 to make the transfer. Read more about Lifetime Plans in our Customer Agreement. Please note that Lifetime subscriptions are no longer being offered to new subscribers.
*There is a $75 fee for each permitted transfer. Each of the fees which you may be charged will be subject to applicable taxes.
I hope this helps some make a decision on if it's a good thing to do or not.