It depends on what type of product it is, as the post-opening shelf life can vary. On each container, you'll find an after-opening symbol that identifies the period during which a cosmetic product can be used after the first opening the packaging. The symbol represents an opened cosmetic jar with a number of months written inside the pictogram.
For example, if the symbol reads 4 M, this means that the product will be safe to use for four months after opening.
However, if the product has not been opened, it can generally be kept for 1 year if stored in a cool, dry place (avoid storing your products in the bathroom).