I'd love the option to give prospective members 15-30 days of access for free, then charged the fee.
Right now it seems like you can rather invite them to be a free lifetime member, make them a paid member, or create 2 groups (one free and one paid).
To get around this (kinda) I am offering a 100% money back offer if they don't 2x their investment, but I think my higher monthly investment will still hold people back.