Mo. Rev. Stat. § 407.334: Contracts, signed by buyer — duration limit — voidable, when — waiver void, when.

1. Every health spa contract shall be signed by the buyer, shall designate the date on which the buyer actually signed the contract and a copy of the contract shall be delivered to the buyer at the time the contract is executed.

2. No health spa contract shall have a duration for a period longer than thirty-six months, but the contract may give the buyer a right of renewal.

3. Any health spa contract which does not comply with the applicable provisions of section 407.330 shall be voidable at the option of the buyer.

4. Any waiver by the buyer of any of the provisions of section 407.330 shall be deemed contrary to public policy and shall be void and unenforceable.