Back when it took me 4 days to do through a big can, I used to portion it out into little plastic containers -- one meal per container -- and put everything but the next day's worth in the freezer. I fed the cats once a day and every time I used one container, I just took the next one out of the freezer so it would have time to thaw. You can thaw in the microwave if you forget, too.
I did keep cans for 4 days and it didn't seem to harm the cats, but they definitely ate the food stored in the freezer more enthusiastically than they ate the food stored in the can for 4 days. So even though it didn't make them sick I assume the taste of the un-frozen food wasn't as good near the end.
I now feed them canned twice a day, and it only takes 2 days to use a big can. I just store in the fridge now, but I do still break the can into 4 meals and store the extra in plastic containers, a meal per can. I think it may store better in the containers (I assume there's a reason we don't store our leftovers in cans with snap-on lids) and it makes it easy to microwave each meal for a few seconds to get the chill off. Also, portioning it out all at once means that the 4 meals are more-or-less equal in size: no making the first 3 meals bigger and the last meal smaller because I ran out!
A suggestion from the pet sitter that works well: Open the can and slide the whole thing out onto a plate into a neat cat-food cylinder. (If necessary, run a butter knife around the food inside the can to loosen it, first.) Use a butter knife to cut the cylinder into 4 sections. (If you need 8 servings, just cut each resulting cat-food puck in half.) Then just stick a section in each container. I generally serve the last section on the plate I cut it on. It's a much easier way to portion out the food equally than scooping it out of the can with a spoon, which is what I used to do. It also makes it easier to make sure each cat gets an equal portion.
The slide-out-and-cut trick works with Wellness, at any rate, as there's no pop-top.. My ladies are not as keen on Evo. I don't think Natural Balance comes in big cans, which is a shame since the ladies approve. I'm stuck feeding the small (5.5 or 6oz, not sure which) size.