A plan is collection of API resources or subsets of resources from one or more API. A plan can contain a mixture of HTTP GET, PUT, POST, and DELETE verbs from different APIs or it can contain all the GET verbs from various APIs. A plan can have a common rate limit for all the resources or each resource can have a different rate limit. Rate limits specify how many requests an application is allowed to make during a specified time interval.
Use this Developer Portal to browse the different plans that are available to you and select a plan that is most suitable for your requirements. Some plans have restricted access that you must request access to use. When you submit your request, the organization is notified, the API administrator assesses your request and they might contact you for more details. Other plans are available to use straight away.
Video tutorial: https://youtu.be/nMS8qU5wens