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.
If you make extra, you can refrigerate clove tea in a pitcher. It will keep for a few days. Store whole cloves in a tightly sealed glass container, and keep them in a cool, dry and dark place, and they can last up to a year. Ground cloves will keep for about six months when stored this way.