N.H. Rev. Stat. Ann. § 110-B:70

The adjutant general shall have authority to prescribe and issue, subject to the approval of the commissioner of motor vehicles, permanent number plates for use on motor vehicles issued to and used for the national guard. Said vehicles displaying said number plates shall be deemed to be properly registered under the provisions of the motor vehicle laws and may be operated upon the highways of the state without further registration or other number plates.