Mo. Rev. Stat. § 265.170
Any fee imposed by sections 265.130 to 265.210 and unpaid on the date on which such fee was due and payable, as provided in section 265.160, shall bear interest at the rate of one percent per month from and after such date until payment, plus accrued interest, is received by the director. If, after due notice, any person defaults in any payment of any fee or interest thereon, the amount due shall be collected by civil action in the name of the state of Missouri at the relation of the director, and the person adjudged in default shall pay the cost of such action. The attorney general, at the request of the director, and, if requested by the attorney general, the prosecuting attorney of any county in which a cause of action arose under the provisions of sections 265.130 to 265.210 for the collection of fees due and unpaid, shall forthwith institute proper action in the courts of this state for the collection of fees or interest thereon due under said sections.
§ 265.170, RSMo