Each person who engages in the practice of fitting hearing instruments shall, on or before the renewal date, pay to the board the required fee, present written evidence to the board of annual calibration of all audiometers, and furnish to the board satisfactory evidence of having successfully completed an educational program approved by the board. The licensee shall keep such license conspicuously posted in licensee’s office or place of business at all times. Where more than one office is operated by the licensee, duplicate licenses shall be issued by the board for posting in each location. After the expiration date of a license, the board may renew a license upon payment of the required penalty fee to the board. No person whose license has expired shall be required to submit to any examination as a condition of renewal, provided such renewal application is made within two years from the date of such expiration and all renewal requirements have been met as set forth in this section.