Can you use your license plate on another car you own?

Yes, you can transfer the registration from one vehicle to another but you have to go through the DMV and pay a small fee.

In countries outside the USA i.e. Uk you will have to inform the DVLA of the change of use and also your insurance company as the vehicles there are tracked by government agencies on motor ways and speed camera areas. Cars that have differing details logged against them in the DVLA database and are scanned on the highway will have the vehicle stopped and in some cases impounded