Understand the Plan Entitlements Page
An entitlement is the relationship between an API and a plan, describing that a plan entitles a client application to invoke an API, and under what conditions.
There is a many-to-many relationship between plans and APIs. A given plan can have entitlements to multiple APIs; for example, to group related APIs. A given API can be entitled by multiple plans; for example, to provide different quality of service criteria. Note that two entitlements of the same plan cannot point to the same entire API, or to the same action in an API.
To view the details of an entitlement:
You can also click the Subscribe button to subscribe applications to the plan.