Mo. Rev. Stat. § 441.100: Tenant giving notice to quit, and failing to do so, liable.

If any tenant shall give notice, in writing, of his intention to quit the premises held by him, at a time specified in such notice, and shall not deliver up the possession thereof at such time, such tenant, his executors or administrators shall from thenceforward pay to the landlord, his heirs or assigns, double the rent reserved during all the time such tenant shall so continue in possession.