Any contract or agreement with an insurance consultant shall not be enforceable by him unless it is in writing and executed, in duplicate, by the person to be charged or by his legal representative, or unless one of such duplicates is delivered to, or retained by, such person when it is signed by him, or unless it plainly specifies the amount of the fee paid or payable by such person and the services to be rendered by such insurance consultant, or unless it is in a form currently approved by the commissioner.