I. The department shall design and issue to every person whose vehicle is registered a number plate or plates for a fee of $4.00 per plate. Such plate or plates shall be furnished by the department yearly or at whatever interval of years the department shall determine. In all cases such plate or plates shall bear on the face thereof a permanent or changeable designation of their effective period.
II. Every vehicle driven in or on any way in this state, if required to be registered hereunder, shall have displayed conspicuously thereon a number plate or plates to be furnished by the department, together with any current validation sticker issued by the department and which has a changeable designation of their effective period. The director may make special rules relative to the number of plates, the location of said plate or plates on the vehicle, and the material and design thereof, provided, however, that number plates for passenger vehicles shall have the state motto “Live Free or Die” written thereon. The plate shall be kept clean.