There is a Standard Symbol for Product Life Expectancy
By Chad Upton | Editor
Finding the shelf life or expiry date on something in your fridge can be challenging. It’s much easier to find the product life on personal items like shampoo, mouthwash, body wash, cosmetics, etc. You won’t find it on all products of this type in North America, but it is a requirement in Europe so you will see it on many products that share global packaging.
The “Period After Opening Symbol” is a standard icon that indicates how many months (M) or years (Y) the product is good after opening. The product must remain harmless to its user within this period.
Now, you just have to remember when you opened it.
Sources: wikipedia (PAOS)