I would like to launch a campaign where the reward is a monthly bill reduction of $1/month for as long as the new customer stays enrolled. The referral and who is still actively enrolled will need...

It looks like you will need to use our API to achieve your goal:(http://invitebox.com/help/api/reward-callback/).

The InviteBox platform will track the invitation process as it normally does, then when a referral signs up or pays for the subscription, (depending on their settings) they will be notified about this event. Everything else will need to be developed on your side: the reward process, monitoring the enrollment of new referrals, etc.