All compensation to licensed professional boxers or mixed martial artists shall be paid by the promoter by check payable to the participating combatant, who shall sign receipts for such payment, unless otherwise directed or authorized by the commission. No boxer or mixed martial artist shall be paid or receive any portion of his or her purse, except for training expenses, prior to the conclusion of the contest or exhibition, except as otherwise directed or authorized by the commission. No boxer or mixed martial artist shall be paid or receive compensation in the form of an irrevocable letter of credit or other such form of payment which might preclude the commission from withholding that combatant's purse should it determine that he or she gave or participated in a sham or collusive boxing, mixed martial arts or sparring contest or exhibition or for other valid reason. No payment shall be made to any person or party other than as set forth herein unless the commission has approved the transaction.