Metered Usage Based on User Numbers

Currently developing an app where the target business model is similar to slack. A given organization is allocated a set of limits. Based on the number of users and/or usage against other in app metrics, a subscription is required to unlock those features and/or additional users.

The subscription would be singular, billed back to an organization and not each individual user. Wondering how Slack and similar apps are managing this with the current guidelines warning for apps that redirect to another payment gateway to handle subscriptions that unlock features.