The card does not name storage conditions or a shelf life: it says “see the packaging”. The method of use is “ready to eat”; the pastilles should be kept out of the reach of children. How long they stay fresh after the packaging is opened, the card does not say.
General information (not a manufacturer's instruction): pastilles are usually stored in a dry place away from heat and direct sunlight, and once opened the packaging is closed tightly so that the pastilles do not absorb moisture.