Iowa Code § 543B.1: License mandatory.

A person shall not, directly or indirectly, with the intention or upon the promise of receiving any valuable consideration, offer, attempt, agree to perform, or perform any single act as a real estate broker whether as a part of a transaction or as an entire transaction, or represent oneself as a real estate broker, broker associate, or salesperson, without first obtaining a license and otherwise complying with the requirements of this chapter.