Me. Rev. Stat. tit. 24-A, § 4102

A society having a supreme legislative or governing body and subordinate lodges or branches by whatever name known, into which members are elected, initiated or admitted in accordance with its constitution, laws, ritual and rules, which subordinate lodges or branches shall be required by the laws of the society to hold regular meetings at least once in each month, shall be deemed to be operating on the lodge system.