Mo. Rev. Stat. § 408.340

The provisions of sections 408.250 to 408.370 shall not apply to retail time transactions consummated prior to the effective date hereof; provided, however, that with respect to any sale made subsequent to the effective date hereof pursuant to a retail charge agreement entered into prior to the effective date hereof, the provisions of sections 408.250 to 408.370 shall apply if (1) prior to the making of such sale the seller shall have delivered or mailed to the buyer a copy of a retail charge agreement, duly executed on behalf of the seller, conforming, except for the buyer's signature, with the provisions of section 408.290, and (2) the seller thereafter complies with all the other provisions of sections 408.250 to 408.370.