To make sure that you can enjoy your herbs for a long time, do not forget to repot them from time to time.
All you need is a slightly larger pot (3-4 cm bigger) and fresh soil. If the pot does not have a hole you should form a drainage layer by using expanded clay or crocks. This allows that water can run out of the pot.
Then simply take out the herbs from their old pot and put them into the middle of the new, bigger pot. Fill the pot with fresh soil around the roots and water the herbs generously.