An Enterprise Use case
You have N enterprise customers, each customer has unique contractual terms. All enterprise customers use same rateplan and products. But each has different renew subscription cycles (12,18,24 months) and each has diff quotaTarget.
You don't want to block them - but have a webhook executed on specific %. (e.g. 90%,100%,110%)
Example of webhook : Charge and Notify customer at 80% of qoutaTarget. Like notification templates are in VerticalResponse/SendGrid (email sending provider), and charging you have in house system.
Having said this, you can think about extending this model to say, notify then block developer by using SuspendApis webhooks etc.
Read more http://docs.apigee.com/monetization/content/specifying-adjustable-notification-plan-details
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