Every license granted by the mayor for the purpose of conducting any business or occupation required by the provisions of this code to be licensed and having designated therein a room, store, office or place in which such business so licensed is to be conducted, shall be posted and during the period for which such license was issued shall remain posted at all times in a conspicuous place, so that the same may be easily seen upon the wall of the principal room, or office, of the store or place in which such licensed business or occupation is carried on, and when such license shall have expired, it shall be removed from such place in which it has been posted and no license which is not in force and effect shall be permitted to remain posted upon the wall or upon any part of any room, store, office or place of business after the period of such license has expired. (R.O. 1959, Ch. 24, Art. 1, Sec. 9)