Joan lite is basically the same plugin with a some significant differences. for example to edit your schedule or to adjust a single show’s timeslot in JOAN Lite you’ll have to delete the entire schedule or show.
With JOAN Premium this limitation is removed and you can edit all of your schedule’s parameters with a few clicks no need to delete existing data to make one minor adjustment.
See Features to further compare
True JOAN Lite does the job but wouldn’t you rather have more features, and priority access to support in case these a problem? Your license not only gives you access to priority support it also gives you access to new features. You need the appropriate license to install JOAN on a WP Multi-site (network).