There is no such medication to treat ED for life long, There are some herbal medicine which improve ED for but this treatment takes its own time may be few months improve male impotency.
And there are some medicine which shows instant result after consumption of this tablets, and it effect last for few ours upto 4-6 hours. Medicine such as Vardenafil ( http://www.medstorerx.com/vardenafil.aspx ), tadalafil, Super P Force, etc.