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.
YOu can store it for a while, but it is easily contaminated. As soon as you pour a quanity out. Clean it( the top), spray with starsan, and stick it in the freezer.
you may want to ask your LHBS what they recommend. If you have the ability I would suggest to break it down in usable quantities so you are handling it only once and not repeatedly.
There is a chance you could freeze it maybe? I have not done it but some people freeze their wort and this is more or less concentrated wort.....