The license shall be issued by the Commissioner of Agriculture upon receipt of a properly executed application form and upon the passing satisfactorily of an examination prescribed by the Commissioner and after having satisfactorily completed a special training course for tester conducted by the dairy department of Clemson University. The license shall be valid for the term of one year and shall be revoked by the Commissioner upon evidence that the licensee has failed to comply with the rules and regulations under which the license was granted. Unless revoked the license shall be renewed annually upon application from the licensee.