Hi could you please tell if I have a criminal conviction if this will limit my eligibility for federal student aid?
Yes it can but make sure you understand your status and don't just assume that you can't get aid, you might well be able to.
What sort of convictions might affect the aid that I can receive?
Other than drug convictions, convictions for a forcible or non forcible sexual offense which are subject to an involuntary civil commitment upon completion of a period of incarceration for that offense your aid might be affected.