They are FREE in Louisiana for seniors, Thank Rick Perry for the fee for us older guy's.
If you go to Louisiana your Texas license is good there so you don't need an out of state one.
Louisiana Law states "Texas residents age 65 or older may fish in any Louisiana public waters (both freshwater and saltwater) as long as they possess any type of valid Special Texas Resident license for seniors and comply with Louisiana law. This includes Texas residents born before September 1, 1930."
Same for Louisiana, if you are 65 or older and have a valid Louisiana Fishing License, it will be honored in Texas.