Every holder of a license to engage in, exercise, or pursue a business, profession, trade, occupation, or privilege, shall conspicuously display the license at all times in some part of his place of business or activity where a person who has entered the place may readily see it; or, if he has no particular place of business or activity, shall carry the license and shall display it to any person who requests to see it. In lieu of the manner of displaying such licenses provided above, when licenses are required for coinoperated music or amusement devices, vending machines, and similar devices and equipment, the license may be placed on or attached to such device or equipment in such position and manner that it will be clearly visible, and shall be so placed or attached if the license so states on its face. It is unlawful to fail or refuse to display the license as required in this section.