How to configure Member2 for existing members with variable renewal dates

Moving an old site into WP. Membership is by invitation/application only. There are about 70-100 members that are currently paid up and active which have to be configured into Member2. How can this be done so that when their membership becomes due a notification will be triggered?

I am assuming that members will be entered manually, but I need help with the variable renewal dates. There is only one level paid membership here. If you need more information, please ask.