California Code, Business and Professions Code - BPC § 6980.33

A licensee, or a partner or officer of a licensee, shall carry a valid pocket identification card, issued by the bureau pursuant to Section 6980.23, and either a valid driver's license issued pursuant to Section 12811 of the Vehicle Code or a valid identification card issued pursuant to Section 13000 of the Vehicle Code, at all times the licensee, or partner or officer, is engaged in the work of a locksmith, as defined in this chapter, whether on or off the premises of the licensee's place of business.  Every person, while engaged in any activity for which licensure is required, shall display his or her valid pocket card, and driver's license or identification card, as provided by regulation.