membership managment

[art4u2]

I need a way for members of my site to be able to log into their own page via password so they get their promised discount from my store. I have been told that there is NO way this can be deducted automatically thru paypal with member password so the ONLY solution is to have a separate store for members only, to enter via, password to redeem their discount. Is this correct? And how can I do this? artataltitude.com