There is a dosage on the bottle that your doctor who prescribed this to you put in your prescription. But your doctor or psychiatrist should have discussed how to take this with you when it was prescribed. If the bottle says as your dosage that you can take 3 in a day, that's the doctor's prescription, but keep in mind, taking this drug regularly will make it harder to stop taking it should you wish to do so. Sometimes you just have to tough things out a bit, and you should look into seeing a therapist who specializes in anxiety who can teach you some relaxation techniques. But again, if the dosage says you can take 3 a day, that comes from your doctor.
You can get that info from your pharmacist or maybe google it if no one here gets back to you with the answer. I think the 3 per day is a toxicity issue and/or also meant to keep you from developing a dependency on it, so use them as sparingly as possible.