can i use jello past the expiration date?

You can almost certainly use it. Depending on storage conditions, temperature and humidity the following will happen. In high moisture high temperature conditions the flavor will start to degrade. This won't hurt you unless it gets so bad that the product is inedible. You might also get some clumping of the gelatin and the whole thing may not set quite as firm.

All in all you have nothing to worry about from a safety standpoint just some product deterioration. Good Luck

PhD Food Chemistry and Nutrition

think so...