The "active" Subscriptions API status has been renamed to "running", to reduce confusion upon future release of the backfill subscriptions capability. More details on Subscription Statuses are available here: https://developers.planet.com/docs/subscriptions/#subscription-status
Pagination has now been added to the GET Subscriptions endpoint. You can see a sample response in our API Reference here: https://developers.planet.com/docs/subscriptions/reference/#operation/getSubscription
Subscriptions API is Planet's new data delivery API which allows you to subscribe to continuous cloud delivery of the imagery and metadata you care about with a single API call. The best of Planet search, processing, and delivery, the Subscription's API's set-it-and-forget-it ordering capability will automatically push imagery to you as soon as it becomes available.