On the Renewals page, you get the list of clients with their Name, Plan, Classes and the End date. Also visible here are Renewal date and the date from which Renewal is auto-scheduled.
From here on, you can manually renew them or take other actions like Stop, Cancel, Edit, Pause and Extend. If desired, you can change the preferred plan, start date, discount etc at the time of renewal.
You can also enable Auto-Renewal at the time of creating plan. For recurring subscription plans like Monthly plan where subscribers generally renew, enable auto-renewal. For plans like summer camp that happen once a year, disable auto-renewal. Subscriptions of clients in plan with auto-renewal enabled will renew on the end date.
In case a client does not wish to continue, you may disable auto-renew from client list or renewal page This way, even if they are enrolled in a plan with auto-renewal enabled, their subscription will not be renewed and their name will be removed from the renewal list.