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.
So, how long does tea last past the best before date? When properly stored, the shelf life of packaged tea past its best by date is approximately... Of course, all foods and drinks last for a shorter period of time if they are not stored properly. But remember that tea, like a lot of other drinks, usually has a best before date and not an expiration date or use by date.