Depends on where you live. If you have a lot of humidity in your area, you need to store it in an air tight bag or box or wrap it well in plastic. After a certain amout of time it does get more difficult to use....not that the iron on part doesn't work anymore...it just becomes harder to get the paper off of the iron on part once the heat and humidity get to it. I buy 5 yards at a time, most of the time. I keep it in a plastic box with a snap on top along with some of my other iron on stabilizers.