Well you can remember how much it was and for how long and how long ago, so that can only be good? ;-P
Sustained use of almost any drug, from alcohol and cannabis to ket and crack, will affect your brain long term. Nobody will ever really know for sure because everyone is different; amounts, strengths and tolerances will alter different people's reactions.
However, the human body is very good at healing itself and I would guess that a healthy diet, exercise and mental stimulation would only help aid recovery.