Rice cakes do expire and when rice cakes expire they do so quickly.
When you open rice cakes they expire much more quickly than when they are sealed.
If you open a package of rice cakes the rice cakes go bad within a day or so of being exposed to the air.
If you leave the rice cakes in the sealed package then the rice cakes will last for up to 1 month before they expire.
Even when sealed it's best to eat the rice cakes within a week of purchasing them because they begin going stale pretty quickly.
Rice cakes don't taste all that good to begin with but when you open them or let them sit too long then they get even more stale and are no longer tasty at all.
So use the rice cakes within a week of purchasing them for the better taste.