The original copy of a weighmaster's certificate shall be delivered to the purchaser of the commodity specified in the certificate at the time of delivery. One copy of the certificate shall be retained at the place of weighing, and one copy may be retained by the business selling or delivering the commodity. Copies of weighmasters' certificates in possession of licensed weighmasters shall be retained for a period of two years and, during business hours, shall be subject to inspection or subpoena for use as evidence by any State, county or city inspector of weights and measures.