§ 172. License required. No person shall open, keep, maintain, own, operate or carry on any employment agency unless such person shall have first procured a license therefor as provided in this article. Such license shall be issued by the commissioner of labor, except that if the employment agency is to be conducted in the city of New York such license shall be issued by the commissioner of consumer affairs of such city. Such license shall be posted in a conspicuous place in said agency.