Licenses issued under this article shall expire on May 31 of each year and may be renewed upon application to the director. Applicants for renewal of a master plumber's or master gas fitter's license shall pay to the county, at the time of filing such application, a fee of five dollars ($5.00), and for a journeyman's license, three dollars ($3.00). (Mont. Co. Code 1965, § 95-27.)