License Plate Locks
You would think that there would be numerous companies that make a lock to prevent someone from stealing your license plate. Well, after extensive searching I could find only one license plate lock by Lock-Um. It uses a license plate frame that has two locks (with keys) to prevent someone from stealing your license plate. The other option is to use tamper resistant or security screws to bolt your license to your car, truck, motorcycle, SUV, trailer, or other vehicle.
Lockum - This company sells locks for cars and motorcycles.