It doesn't have a date on it anywhere? I haven't used the Wilton brand before, but I have bought the bucket from Sam's. It has a date printed on the label, about 8-10 months usually from when I purchase it. With the fat content, I would think you'd be able to tell when you open it if it went bad. (It would have a rancid smell.) On second thought, Crisco keeps almost forever...so it may keep about as long too.
I checked the Wilton product site, it doesn't mention shelf life either.