Every driver operating a state, county or city owned motor vehicle or motor cycle exclusively for the use of the state, county or city shall be licensed to do so without charge by the commissioner in accordance with this chapter. A special certificate, to be prescribed and furnished by the commissioner, shall be issued to him. The license so granted shall, unless otherwise revoked, terminate upon the licensee’s ceasing to be an employee of the state, county or city, and it shall, upon demand made therefor by the commissioner, be surrendered.