Ground Chili Powder has a shelf life of up to 3 years so your Chili Powder if stored properly in the sealed container will last up to 3 years but it may still be good after 3 years.
If the Chili Powder is over 3 years old it still may be good to use but it may turn hard and have to be broken up to use it.
Always store the Chili Powder in as dry of a place as you can and keep the sealed tight on the Chili Powder to prevent it from hardening up too soon.