Your Tennessee driver license stays valid while you are on active duty and stationed outside Tennessee. You can have a "Code 30" put on the license so that it does not expire. It stays valid unless you surrender it or it is canceled, revoked or suspended, or until you are discharged or reassigned to a duty station in Tennessee. You then have 60 days to renew.
Add the "Code 30" at a Tennessee Driver Services Center, or mail the completed military checklist and the documents it lists to the Tennessee Department of Safety and Homeland Security, Driver Services Division – Special Handling, Attn: Military Coordinator, Browning Building Room 253, 1150 Foster Avenue, Nashville TN 37243 (use 37210 for overnight shipping).
The completed military checklist, your military orders or ID showing active duty status, and the supporting documents listed on the checklist.