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.
Assuming it was also kept in a cool, dark place, Iâd say 2 years if kept in a tightly seal tin or 6-8 months in a sealed bag. But your tea is 3 years old and was kept in a bagâ¦.it wonât be bad, just kinda stale. I never keep any bagged tea for longer than 6 months.