Section 40. Each vehicle used for the transportation of bovine or porcine animals by any person engaged in the business of dealing in such animals, when operated on any way in the commonwealth, shall bear a metal license plate, attached to the side of the vehicle to the left of the person operating or driving the same, such plate to be furnished by the director upon the payment of a fee, the amount of which shall be determined annually by the commissioner of administration under the provision of section three B of chapter seven. Said plate shall be valid for the term for which the license is granted, but shall be returned to the director on revocation of said license.