If you are going to go to a therapist, you should just tell them everything, drug use included. The only reason they are there is to help you, and they can't do their job fully and to the best of their capacity if you lie to them. If you are going to lie to your therapist, you might as well not even go because it will be pointless. It isn't like they can tell anyone what you say anyways.
the last psychological evaluation I had was court-ordered. I was in juvenile and the guy who interviewed me knew I was lying to make myself sound more normal.
