Section 15D. A lessor who has agreed orally to execute a lease and obtains the signature of the lessee shall, within thirty days thereafter, deliver a copy of said lease to the lessee, duly signed and executed by said lessor. Whoever violates any provision of this section shall be punished by a fine of not more than three hundred dollars. Any waiver of this provision in any lease or other rental agreement shall be void and unenforceable.