All beauty products need to be used by a certain period. This is known as the 'period after opening' and can be easily identified by the PAO symbol. The symbol can be recognised as the shape of an opened jar, and will have a number inside; 9M will indicate 9 months, 12M is 12 months, and 36M is 36 months. Once opened the product should be used in this period, as after this time the quality of the product will deteriorate.