Packaged, loose or powdered teas all last about six months to a year in the pantry. The shelf life of tea can depend on many factors such as how it was stored and the "best before" date.
Tea usually has a "best before" date rather than an expiration date like many other foods. You can still safely use the tea even after the "best before" date, but only if tea has been properly stored. To keep tea fresh, store it in the freezer. After preparing tea, keep it in the refrigerator tightly sealed to ensure your tea is fresh every time.