It only takes a few seconds. Find the little open-jar symbol on the back of your product (it's there on almost everything -moisturizer, foundation, mascara, sunscreen, you name it).

The number inside tells you the shelf life after opening, in months. Write the date you opened it on your Bewty Mark label, stick the label on the product, and you're done.

When the months are up, you'll know - no more guessing, no more squinting at tiny print, no more "is this still good?"