Me. Rev. Stat. tit. 22, § 689

Except for consumer products, it is unlawful for any person to use, manufacture, produce, distribute, sell, transport, transfer, install, repair, receive, acquire, own or possess any source of radiation, unless licensed by or registered with the department in conformance with rules, if any, promulgated in accordance with this Act. Notwithstanding this paragraph, licensing or registration of specific consumer products may be required by the department by rule in specified circumstances.