Throughout the API reference, you will see references to these two permissions:
admin: Gives an API application read/write access to all resources across all events, such as creating registrations at an event.internal: Gives an API application read access to internal information, such as retrieving a list of events a user has access to.
Both of these permissions can be granted by an admin. Please talk to either tjhorner or tylermenezes if you believe you need one of these permissions.