This is useful for setting up corporate/organization/domain- based subscriptions on your website. Licensing options are available. If the user limit is set as 100, only 100 users with the mentioned domain in their email addresses would be able to access the premium content. Once the mentioned user limit is reached, no more users can access the premium content as part of this subscription group.

How to create group subscriptions: 
https://docs.google.com/document/d/14BcR5QRZTdlaa9iN5HFuWSu0rzB9AVPt3_rJGwUHaiI/edit