(a) A license issued under this chapter expires on the second anniversary of its effective date and may be renewed as provided by this subchapter. A person whose license has expired may not engage in an activity for which a license is required until the license is renewed.
(b) The executive commissioner by rule may adopt a system under which licenses expire on various dates during the year. For a year in which the license expiration date is changed, the department shall prorate license fees on a monthly basis so that each license holder pays only that portion of the license fee that is allocable to the number of months during which the license is valid. On renewal of the license on the new expiration date, the total renewal fee is payable.