The period-after-opening is symbolised by a figure following by the letter M (for "month"), inserted in a open jar. It shows a maximum recommended period of use, for which, according to the european regulation, it is "without any harm to the consumer".
 12 M means that the cosmetic product can be used without problem during 12 months, as from the day when its packaging was openedfor the first time. After this period of time, the product risks to lose in quality or in microbiological security, sometimes only in texture or in colour.

Important information, which requests all the same that the consumer have an active role : then it is advised to note (on the packaging) the date of the first opening , only guarantee that this logo is used for something…

The open jar is compulsory for the cosmetic products which can be used beyond 30 months after their manufacture. For the other products, only a date of minimum durability is planed by the regulation.