Most LME come in 3 pound cans, which is a quite large quantity if you want to add just a little to your wort, just one pound for example. It's a shame to throw away the rest. If I open a LME can and do not want to use the whole amount of lme, can I save the rest for later, even in a refrigerator? After all, it already contains water so it doesn't have the hydration problems of DME, and, furthermore, whatever the time i decide to use it, I will boil it for sanitation first. What do you think?
Yep. Seal it up with some plastic wrap and a rubber band. Or, better, in air-tight tupperware and keep it in the refrigerator. Limit exposure to oxygen and you should be okay.
Taste it before using again to check if it's stale or off.
Foodsaver makes tupperware-type containers with vacuum valves that allow you to suck all the air out of the container. Put your LME in one of these, sucky-thing it, then store it in the fridge for a little while.
No you can't save it. You really can't limit the Oxygen exposure very well and it will eventually stale. Not to mention is somewhat hyrgoscopic so its going to try and absorb moisture from your fridge thereby sucking up odors from your fridge as well.
The best bet is to be using a mix of liquid and dry. Use LME for the bulk of your extract needs until you can't use a full can anymore. Then switch to dry to take you to your desired total extract points.
Alexanders does sell small cans of LME called kickers. I think these are half pound each. You might also want to look for some of those.