resumeIn brief
Before buying, decide which part you will use immediately and whether the rest can be stored for another dish.
Useful to know
Fresh herbs are good to buy with a specific use, because a recipe often requires only a small part of the bunch. Iowa State indicates possibilities for fresh use, drying or freezing. For some connections, it describes storing with stems in water and covering in a refrigerator. [1]
The technique should not be taken as equally suitable for any aromatic herb. See what kind of product you have and prepare only the necessary part for the dish. Leaves, stems and the moment of addition can have a different role according to the recipe.
A practical plan is to associate the purchase with two dishes: for example, a fresh finish of a salad and a sauce addition. This is a proposal for organization, not a claim for an exact expiration date. Do not use a rule to replace fresh with dried herbs as a universal measure for all species.
Sources
For further detail and to check the information: