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.
1. So Fresh Over time the oils in tea can break down. This can affect the way it tastes, so itâs best to buy tea from a store with high turnover. Tea can last up to two years if itâs stored in a cool, dry place (try an airtight container). It shouldnât make us sick after it passes the expiration date, but tea will taste best if you use it within six months.