Yes paint does expire and the easiest way to figure out if your paint is expired is to smell it. Expired paint smells terrible nothing like when you bought it. Latex paint will last a few years if stored properly. Make sure the lid is on tight and it doesn't freeze. Oil based paint can last longer than latex if the lid is sealed. It is a good idea to check your paint once a year and shake it up and/or stir it.
Can Paint Expire?