The container of "my" soy-milk specifically says not to freeze it, though I don't know exactly why. I use a brand of "shelf-stable" soy-milk with no other additives (i.e., only ingredients are water and beans), so that's where the following comments are coming from.
I go through about a quart a week, so I buy quart-size containers and go through it before it goes bad. This is probably obvious, but probably your best bet.
As for freezing, I tried to make soy-milk-based frozen popsicles a couple of times, and the results were undesirably grainy; I think the soy milk didn't freeze evenly (there were other ingredients, but it "felt" like particulates from the milk). Even after thawing, the texture and consistency wasn't quite right. YMMV; freezing behavior likely depends on the brand -- for instance, how the milk is made, how it's processed, and how any additives (emulsifiers, thickeners, or stabilisers, such as carrageenan or xanthan gum) happen to respond to freezing/thawing.
For practical concerns:
- expansion when freezing -- make sure your containers won't explode!
- separation -- shake well before and after freezing! Some soy-milks have additives (like above), so this might be less of a concern for those.
- texture -- I found that after a freeze-thaw cycle "my" soy-milk changed in consistency. It was "off" in some way that I can't really qualify. It may be less of an issue when the milk is used "in" something else.
Some additional thoughts can be found at can you freeze this, but sounds to me not much more than speculation.
Have you tried it? I'd be interested to hear what your results from "your" milk are like.