Take the plate off yourself and return it to DMV. Otherwise when you transfer your insurance to your new car, the insurance company will notify DMV that your insurance has been cancelled and you will get caught up in bureaucratic red tape having to prove that you no longer own the vehicle. Easier to just head that off by returning the plate before DMV gets the notice of cancellation.
quote: Plates, depending on when they expire, are transferred to the new/used vehicle you purchased from the vehicle traded in/sold. There is some paperwork involved, but in the end you use the same plates.
She's in Louisiana. It doesn't work that way here.