In theory, gin can be stored indefinitely. As a rule, gin has a minimum alcohol content of 37.5% by volume and therefore does not require a use-by date, according to the Food Labelling Ordinance.
However, this only applies to alcoholic beverages that have an alcohol content of over ten percent by volume. For gin, this means that no spoilage germs can form and that a long storage time does not have any adverse effects on health.
Nevertheless, gin that has been open for years can lose a lot of its flavour. The reason for this is oxygen, which leads to oxidation and evaporation of the alcohol and the aromas. However, this does not happen in a few days, but usually takes several months or years. However, if you have many gin bottles open, this can become a problem at some point.