Yes, beauty products also have expiry dates, and just like the food in your pantry, they too have ideal storage temperatures.
Lets start off with expiry dates. It's normally listed on the product itself, but sometimes is written only on the outer packaging also - so beware! You're looking for a tiny little open jar with a number, normally 12, listed as "12M".
I'm sure your eyes have skimmed passed it a few times and dismissed it (like me!).
This means, the product from opening is A- Okay to use for the next 12 months, and after that timeframe- well, who knows what might be growing in there (sorry!). As soon as you've opened a product, it begins to oxidise, hence, is less effective. Unfortunately, just a part of life. Picture this, you've cut into an apple, and after a while it starts turning brown. Your beauty products are the same - just a very, very expensive apple.