Before you can use an API you have to register your application. When you register an application, the application is assigned a unique client ID and client secret. You must use the client ID when you call an API that requires you to identify your application by using a client ID, or a client ID and client secret. Check the API description for the details.
Select a plan
Finally, now that your application is registered, you need to subscribe to a plan. The plan determines the number of API calls that your application can make. Some plans are free and no approval is required, some require approval, and some require approval and a monthly subscription. Think about what you need and choose the most suitable plan.
All done! You are signed up, registered, and ready to go.