I know already that if somebody responds to an invitation and does not complete the signup, the invitation will expire. But are there any other things which cause expiration? For example if someone waits too long to reply? What is the time period for an invitation to be good, if there is one. Thanks!
I think it's the length of time it takes them to respond. 90 days.
Thanks FedMedic! Can anyone at Ning confirm this?