No person, except as described in section 27.03, shall be required to hold more than one license in order to engage in any aspect of food handling described in section 28A.05 provided, that each issued license shall be valid for no more than one place of business, except that a license for a mobile unit or a retail food vehicle, portable structure, or cart is valid statewide and is required to be issued only once each year unless the licensee fails to display the license as required by section 28A.07 or it is a seasonal permanent food stand, seasonal temporary food stand, food cart, or special event food stand as defined in section 157.15, in which case the duration of the license is restricted by the limitations found in the definitions in section 157.15.