Dry dip mixes do expire.
Dry dip mixes are good for up to 18 months to 2 years after the expiration date.
Properly stored, a package of dry dip mix or salad dressing mix will generally stay at best quality for about 18-24 months at room temperature.
The best way is to smell and look at the dry dip mix or salad dressing mix: if the dry dip mix or salad dressing mix develops an off odor, flavor or appearance, or if mold appears, it should be discarded.
Although even after the dry dip mixes or salad dressing mixes expire they are still safe to use and consume as long as there's no mold in it.
The taste won't be as good as fresh dry dip mix or fresh dry salad dressing mix.
But the expired dip mixes or salad dressing mixes will remain safe to eat and use.