A Mississippi professional license issued under Title 73 will not expire while you are on federal active duty, and stays extended until 90 days after you return. You only pay the normal renewal fee, with no late or delinquency charges.
Contact the Mississippi licensing board or agency that regulates your profession and give them a copy of your official military orders or written verification from your commanding officer before the 90-day period ends.
A copy of your official military orders, or written verification of your service from your commanding officer.