Me. Rev. Stat. tit. 32, § 1358

A person holding a valid license under this chapter on the date of entering employment in the Armed Forces of the Government of the United States during a period of war or employment in any wartime service outside of the continental United States, governmental or otherwise, under the United States or any of its allied nations is exempt, for the duration of that employment, from the payment of all renewal fees, and the licensee's license remains in full force until the next regular renewal date following the termination of that employment.