N.D. Cent. Code § 39-04-14.1
Except as otherwise provided in this section, the registration of a motor vehicle whose registered gross weight does not exceed twenty thousand pounds [9071.84 kilograms] expires on the last day of the month which is the anniversary of the month it was originally registered. The registration may be renewed annually on application by the owner and payment of fees required by law. The renewal takes effect on the first day of the first month of the registration period. An owner of more than one vehicle qualifying for staggered registration under this section may renew all of the owner's vehicles in the same month. The director shall prorate the registration fees accordingly. If a previously registered motor vehicle whose registered gross weight does not exceed twenty thousand pounds [9071.84 kilograms] is purchased during the period the vehicle's registration in this state is expired, the department shall collect the annual registration fee under section 39-04-19 and shall issue registration that expires on the last day of the month that is the anniversary of the month the vehicle was purchased.
N.D.C.C. § 39-04-14.1