The secretary shall issue an ambulance, organ transport vehicle, or aid vehicle license for each vehicle so designated. The license shall be for a period of two years and may be reissued on expiration if the vehicle and its equipment meet requirements in force at the time of expiration of the license period. The license may be revoked if the ambulance, organ transport vehicle, or aid vehicle is found to be operating in violation of the regulations promulgated by the department or without required equipment. The license shall be terminated automatically if the vehicle is sold or transferred to the control of any organization not currently licensed as an ambulance, organ transport vehicle, or aid vehicle service. The license number shall be prominently displayed on each vehicle.