Do you have to refrigerate cat food?

It depends on the type of cat food. There are three types. Dry, moist and sem-moist. Dry cat food can be left out all the time allowing the cat to graze at will. It is highly convenient for us and and our cat and cheaper than wet and semi-moist. But it is not entirely healthy for a cat when used as an only food because it contains too much carbohydrate and not enough water. Dry cat food tends to lose its nutritonal value over time in storage  - max about 6 months.

Wet cat food, as you no doubt know, smells when left open on the dish for a time. It goes off and cats like the smell of freshly opened wet cat food. They tend to leave wet cat food that has been left on the dish for a while, say about 30 minutes depending on the ambient temperature.

Unused and opened wet cat food should be covered and refrigerated. Personally, I would buy wet food in sachets and give it all in one go. Anything left I feed to wildlife and they eat it all. It is an efficient way of using all of the product.

Semi-moist cat food comes in small cans and should be used in one go. Waste can be dealt with as above or unused food can be refrigerated as for wet food. Semi-moist cat food is high in sugars too.