Mo. Rev. Stat. § 1.170: Repeal of law not to affect rights acquired thereunder.

The repeal of any statutory provision does not affect any act done or right accrued or established in any proceeding, suit or prosecution had or commenced in any civil case previous to the time when the repeal takes effect; but every such act, right and proceeding remains as valid and effectual as if the provisions so repealed had remained in force.