Trial Memberships

We have added a Trial Membership good for 30 days. We hope this will drive players to a paid membership. We only want players to be able to sign up for this one time. We currently are having to monitor the new signups to the membership so that it's not abused. It would be nice if the Trial Membership was preloaded in CR and restricted to a single use or if there was a way to toggle it to one use only. I see where we can expire and move it to another membership and we have that set to send them back to a guest membership. If the membership would had a check box to Require Approval I think that would help us manage this.