There seems to be quite a bit of 'folk-law' regarding registration, de-registration and re-registration of Garmin units particularly in regard to LM. Regardless of the Garmin account holding the registration, if you have bought a second-hand unit from it's legitimate owner you may continue to update it, Lifetime map update included, without problem.

I have an NA 1450LMT [US&CA] bought from a retired couple who obtained it in LA for tripping around the States. A friend of theirs had opened a Garmin account for them and registered it. They gave me the account login details because they didn't want the account anyway. However I wasn't able to get the correct password so the unit remained registered to that account. I asked them to contact Garmin but nothing happened for almost a year when the account was finally closed by their friend in the States. I had no problem updating the maps using both GarminExpress and MapUpdater during that time anyway.

There will only be a hitch if you try to register it in your Garmin account without the previous owner de-registering it. If actual registration matters to you, ask the previous owner to remove it from his Garmin account and then you can register it. If you've bought a stolen unit you'll definitely have a problem if the rightful owner has reported the theft of their registered unit to Garmin. The map update with be refused: 'No map updates are available for this product. Please contact Garmin support' or some similar message with be given. I'm not sure of Garmin's 'further action' policy if somebody tries to register a stolen unit on their Garmin account. Perhaps it varies depending on the Country, perhaps they do nothing, but maybe they'll quietly pass over to your local police the account info connected to the unsuccessful registration attempt. Of course then if the unit is recovered it will be returned to it's lawful owner without compensation to you. Worse, if you can't prove that you bought it in good faith and are able to show supporting documentation you may be charged with stealing or conversion/receiving stolen property. Best not to buy one 'off the back of a truck'/'in the pub' from an untraceable anonymous seller. Buying from eBay using PayPal gives you some protection at least. I can't say for elsewhere, but here licensed 2nd hand dealers must guarantee the title of the goods they sell so buying from them is relatively safe. The smart and honest ones will check for any current registration before buying/pawning a Garmin. I've personally known of one instance where the dealer had registered the unit but then forgot to remove it from their Garmin account after the sale. Copious 'sorry sorry sorry' resulted and the unit removed post-haste.

Garmin here will even actively assist you by attempting to contact the previous owner [if it's registered already] regardless of their stated policy of LM subs not being transferable as i said in Post #3. It would be interesting to hear what users have experienced elsewhere in the world as to if and how Garmin's local policies and procedures differ.