It shall be the duty of every person to whom a taxicab license is issued to post such license certificate in a prominent place upon the premises of the headquarters from which the business is conducted and to keep such license certificate so posted as long as such business is conducted thereunder. The licensee shall not permit such license to be obscured or concealed in any way, so that such license will not be readily visible at all times to persons lawfully present on such premises.
(1956 Code Sec. 583.14)