I think that there was a 4.5, although I never had that. That was the first AGA version.
I do have DPaint5 on CD which I've used little as, on the A2000, I just use PPaint, TVPaint, and ImageFX.
-- Were YOU referring to the Registration No? In DPaint5, that is on the front of the manual. Why not request, of the seller, that he send you the number?