Atomic Fireballs do expire and are usually at their best quality for 1 year.
However Atomic Fireballs and most other candy do not go bad in that it will harm you and as long as they are stored properly the hard candy including Atomic Fireballs are safe to eat decades after they are made.
Hard candies do not go bad or spoil like other foods will and are safe to eat many years past the expiration date.
While the quality of the candy will change and not be as good it won't make you sick to eat old and expired hard candies.
I've eaten hard candy and other candy that was 10 years old that my Grandma had left in her house when she died.
There was no need to throw it out as it was completely safe to consume.