But with an airtight lid, 24 hours should be okay.

It's a big can (5.5 oz.) and I only have her a teaspoonful full.

Still, if you have a tight-fitting lid, you should be able to keep it for the 3-5 days recommended. Just don't leave it out on the counter for any length of time--this time of year.

I can't give it to my cats straight from the fridge. It would be too cold for them.

You could either leave out just the portions you've dished up, or maybe nuke it in the microwave at 10% power for 10 seconds or so.

Or add a bit of warm water?

5 minutes should do it. I wouldn’t microwave it, but a tiny bit of warm water couldn’t hurt. Many cats do not drink enough and if the bulk of their meal is dry kibble, then it would be helpful.

They drink water like it's going out of style. I'm constantly buying litter!

of the food back in the refrigerator while you let the bowl you intend to feed reach room temp for a little bit--that small amount should take more than 10 minutes or so.

...seven days at 41 degrees or below.

fitting lid. Should be good for about a week.

Canin Renal diet food. One 6 oz can lasts about four days. She is twenty years old and doing well, so far. 🤞