Ubercart

I'd like to stop people who have already subscribed to a membership from subscribing to the same product once they're a member. You'd think people would be smart enough not to do this..... but you know how it goes.

Was trying to see if there was something in the node object referring to the role granted so I could tweak the theme to prevent a subscribe button from appearing based on that, but can't see anything like that. Is there a way I can get that info in the template?