Can I use the original 1 gallon (plastic) containers that the TreeTop apple juice came in to bottle my apfelwein when it's done? It might be several months before it all gets consumed.
I wouldn't recommend bottling in plastic that isn't designed for reuse. The oxygen permeablilty of the container, combined with the potential for plastic leaching, could spell out disaster for your brew.
One gallon glass carboys can be had for cheap at any lhbs, and most health food grocery stores also stock apple juice in them. If you buy your juice prepackaged in a glass carboy, you end up getting a really good deal on the carboy, and you get some rockin' juice to start your apfelwein!