Toldeo Bend

Do I just need one fishing license to fish this lake or do I have to have a Texas freshwater and a Louisiana freshwater license as well?
Also does the bag limit on this lake according to TPWD apply to the whole lake or just the Texas size of the lake?

Your Texas fishing license is good for the entire lake. Not positive on the other so will let someone else answer.

A fishing license is required when fishing on Toledo Bend Reservoir. Since the lake is bounded by both Texas and Louisiana, a fishing license from either state is valid for residents of either state fishing on any part of the lake (not from the shoreline!). For visitors who will want a temporary license, where you are staying (Louisiana side or Texas side) is not particularly relevant so long as you will be fishing on the lake and not from the shoreline. Therefore, generally, you may be staying in Louisiana and could fish with either a Louisiana or Texas temporary license - or vice-versa.

Bag limits are the same for either state on Toledo Bend.