Every person with a certificate and conducting a business at a fixed place of business located within the city shall post the certificate in a conspicuous place at the place of business. All other persons, their employees and agents, shall carry the certificate, or a certified copy, with them at all times while conducting business in the city. All persons with certificates under this chapter shall produce the certificate upon the request of any police officer or any person designated by the tax collector. (Ord. 1921 NCS §2 (part), 1993.)