I've brought a private registration, what do I own?

Technically, you cannot own the registration. Like your passport or driver's license, you don't own it, but you have the right to use it. Registration ownership is with the Government (Secretary of Transportation). You are entitled to associate the registration with your vehicle or retain it for future use. Once you assign a registration to a vehicle, you can keep it on that vehicle for as long as you like and transfer it to subsequent vehicles as many times as you like.