The best advice I can give you about storing raisins is to store them in a dark, cool, and dry place. Light, moisture, and heat should be avoided entirely to maximize shelf life.
But there’s more. Don’t expect nothing will happen to your raisins in their original container. They often come in a cardboard container that can be easy for bugs to dig into.
So, if it came in a cardboard box, you should take them out of its cardboard box and store them in an airtight container.
If possible, try to store them in smaller containers. When you open a container, it’ll get exposed to air quickly, and chances are you won’t eat a 1-pound portion of raisins at the same time. So, what I like to do is I like to store them in half-pint canning jars.
Throw an oxygen absorber into each canned jar can to keep them extra fresh.
After you throw in some oxygen absorbers, storing them in a really cold place can extend their shelf life by 1.5-2x what it typically is. Freezing raisins are the best option, but a refrigerator can also extend its shelf life significantly.