This is shown by a little picture of an opened lid and a number of months beside it.

This indicates how long you should use the product from the time of first opening it. Now you might think this is a ploy by the cosmetic companies to make you go through more product but in fact this is something you should really pay attention to as a lot of products contain active ingredients that can become inactive after a certain amount of time, therefore making the product ineffective.

Your skin is a precious thing and using products that you've had for years is not really showing it the respect it deserves.

Be nice to your skin and it will be nice to you.