Mo. Rev. Stat. § 429.630: Brokers, appraisers and title examination service at time of closing to give written notice of right to lien on premises — failure to furnish notice, effect.

Any real estate broker who proposes to assert a lien pursuant to sections 429.600 to 429.627 or any certified real estate appraiser or any person performing title examination services who proposes to assert a lien pursuant to section 429.629 shall be prohibited from asserting such lien unless, at the time of the closing for such transaction, such broker or appraiser has given written notice to the purchaser of the commercial real estate that payment of the broker's or appraiser's fee or title examination fee is due and that he or she is entitled to a lien on the premises.