A tablespoon is a non-scientific but very widely used unit of volume, which works very well in cooking, herbal medicine, etc. It is represented by a capacity of one tablespoon which varies from roughly 15 mL in the US to 20 mL in Australia.
1 If tea is properly stored, it can potentially last up to a year for green and black teas. White tea lasts about six months before it isn't as good in quality as when fresher. Stale tea (or bad tea) will taste flat, as if you're drinking paper.  Glass or ceramic containers are fine provided that they're opaque.
Unopened, packaged tea can last a year beyond any best by date stamped on the package. Does tea expire? Tea will eventually loose its flavor, but dry leaves will last a very long time. The shelf life of tea depends on a variety of factors, such as the best before date, the preparation method and how it was stored. Tea, made from the leaves of the Camellia Sinensis plant, is enjoyed both hot and iced.