Mo. Rev. Stat. § 47.210

When any credit shall be given upon the sale of any lot for any part of the purchase money, the purchaser shall give his note or bond with sufficient sureties to the commissioner, for the use of the county, to secure the payment of each installment; and the commissioner shall deliver to the purchaser a certificate describing the lots sold, the price, the amount paid, if any, the balance to be paid, when due and how secured.