What Kanegasi said. And you can't always rely on garbage collection for things like strings either, especially during events that trigger much like OnUpdate. Though, garbage collection is slightly more forgiving for strings... if only a little. Addons should have an initialization phase for every table where it's created and at any point you need to reset/reuse, or wipe, it you should use table.wipe.
I'm not sure how they're using the table but a reference/key can be read either as a string or a variable.
Lua Code:
BA_Data1["AAAA1"] == BA_Data1.AAAA1
So
Lua Code:
--upvalue table.wipe for ease of use and performance
local wipe = table.wipe
local BA_Data1 = {} -- should be the only place you set it as a table
-- stuff happens
BA_Data1.AAAA1 = wipe(BA_Data1.AAAA1) -- that should solve the memory issue