Every certificate of license issued shall be posted by the licensee in a conspicuous place upon the wall of the building, room or office of the store or place in which such licensed business, calling, trade or profession is carried on, so that the same may be easily seen, and when such certificate of license shall have expired it shall be removed by the licensee from such place in which it has been posted; and no certificate of license which is not in force and effect shall be permitted to remain posted upon the wall or any part of any room, store, office or place of business after the period of such certificate or license has expired. It shall be the duty of each and every person to whom a certificate of license has been issued to show the same at any proper time when requested so to do by any police officer or license inspector. (Prior code § 20-1-15)