You'll need to add an Advanced filter to your userlist to query the database and see if they've an active subscription or not. The below should work fine.
Code:
( ( SELECT COUNT(*) FROM `#__cbsubs_subscriptions` AS sub WHERE sub.`user_id` = u.`id` AND sub.`status` = 'A' AND sub.`plan_id` = PLAN_ID_HERE ) >= 1 )
Replace PLAN_ID with the ID of the plan you want to check for. Once done and added to your userlist it should only show users actively subscribed to the plan you specified.