Depends entirely on your doctor, but they come in boxes of four, and you'll probably get two boxes (enough for 16 punts for most people).
Then it's on your record, and you just need to put in a repeat request from then on, without having to have an appointment each time.
Note : on a proper prescription you aren't paying per tablet or per box, you are paying the standard charge per item, regardless of what you get and how much of it.