My LHBS has 33lb Containers of LME, at quite a cost savings to buying kits or the 3.3 lb canisters. How well would the opened stuff do in a refridgerator. For me that would last about 6 months (around 5-6 batches).
Probably do better in the refrigerator but mines always full so I just leave mine in my brew closet. I've also heard that you should put in some vodka/alcohol to make a thin layer over the top to help protect from mold.