Sorry about your grandmother! Sending heartfelt condolences ❤️

As others have said, beverages such as whiskey are generally considered to be non-perishable due to their high alcohol content. They won’t “go bad” in the sense that they’ll be harmful to you if you drink them, but the flavor may change after a long time. If you have pleasant memories of your grandmother, I’d keep them in a sturdy box that’s for sentimental items!