A well dried herb keeps for a year, and a badly stored one for a few months. The difference lies not in the drying but in where we put it away.
Light is the greatest enemy. A glass jar on a shelf by the window is the prettiest and the worst way: the colour fades, and with it everything else. A paper bag in a dark cupboard looks plainer and works better.
Damp comes next. The herb must be completely dry before it is stored; a leaf must rustle and break, not bend. If it bends, there is still water in it.
Air does the least harm, but we close the jar all the same. We do not tip blends together into one container; each has its own scent, and after a few weeks they all have the same one.
On the container we write what is inside and when it was gathered. Half a year on, that is no longer obvious.
This answer is general in nature and does not replace a visit to the doctor. The products are foods or cosmetic products and do not replace medical treatment.