Once herbs or spices are ground, they generally last up to 2-3 years.
Here at Zizira, we always advise our customers to store their herbs and spices in a cool and dry place as they tend to last longer that way. Moreover, if you store them in an air tight container, they retain their flavour and potency so long as you don't expose them to oxygen on a consistent basis.
This is also one of the reasons why herbs and spices that are still sealed in their original packaging are okay to use past their date of packaging. As long as they are still sealed, the aroma and flavour will continue to be there. Remember to open your herbs and spices container only when needed to avoid loss of aroma and flavour.