Md. Code, Transportation § 13–605

(a) The temporary registration of a vehicle under this part expires on the first to occur of:

(1) Receipt of annual registration plates for the vehicle;

(2) Rescission of the contract to buy the vehicle; or

(3) Expiration of 60 days from the date the temporary plate was issued.

(b) The Administration may extend the temporary registration for a vehicle under this part for a period not to exceed 30 days if the Administration is satisfied that reasonable conditions exist to justify the granting of this extension.

(c) The person to whom a temporary registration plate has been issued for a vehicle shall destroy the temporary registration plate as soon as the temporary registration expires.