Adderall dependency and dosage over time?

I suffered through school with ADD and my coping strategies for my ADD related depression were not healthy. At 25 as my responsibilities increased I decided to try adderall. It has done wonders and I finally feel capable in carrying out tasks that used to make me frustrated and panicky. Since taking adderall I am eating healthy and have stopped drinking entirely. I can stay in contact with people whereas before I often lost contact due to forgetfulness and distractions. So far it has been great! That being said, I do have a few fears. 1) If used as prescribed will I develop a dependency issue? 2a) Will my dosage always have to increase as I get older 2b) what I mean is will the benefits of adderall go away after prolonged use leaving me with a dependency on adderall with no real benefits or will the same dosage keep me productive provided it is not abused.