Properly stored paint can last for years which is great if you need to make a small touchup. The catch I hear from most though is it was almost impossible to get the lid off & when they did it was dried out or had rust inside. In a lot of cases the issue was with how it was originally put away.
See the issues with all the caked on paint filling the rim – well that not only made it impossible to close properly but made it extremely hard to open. The fix?
Just simply add a few holes inside the rim area to allow paint to flow back into the can – you can use a large nail, a screwdriver or a painters 5 in one tool. Not that I paint often but I generally put those close to where I will pour the paint out from & do it before over a drop cloth or cardboard. I know some like to wait till they are almost done but that can allow for dried paint or you to kick paint in the rim out.