Buying makeup for yourself can be confusing, whether it's from a department store or drug store.  But wondering how long you keep it can be another.  Well here's a tip... some cosmetics companies will actually illustrate on the back of the packaging how long they're suggestion the products shelf life is. In the photo below Maybelline is saying the shelf life for this mascara is 6 months!  

Here's a list of how long to keep certain beauty products:

• Mascara*: 3-6 months
• Eyeliner* (Liquid & gel):   3 months
• Foundation (Liquid): 6-12 months
• Concealer:  6-12 months
• Lip Gloss:   1 year  
• Eyeliner (Pencils):   2 years
• Powder Products (eyeshadow, blush, foundation):  2 years  
• Lipstick:   2 years
• Nail Polish:  2 years

*If not used everyday, stop continuation of use (and replace) at 6 months!  Extended use of expired products, especially around the eyes can cause irritation and infections. 

Here's a few more examples. Sometimes the icon is small and can be hard to see. Or a bit larger and extremely visible.