Send what happens to other apps, and let them work with your platform.
Connect apps (Your platform → Connect apps) does two things:
Webhooks: new members, payments, finished lessons, sign-ups, questions and more, sent to Zapier, Make or your own code as they happen. In Zapier, pick Webhooks by Zapier → Catch Hook, paste its address here, and press Send a test. Deliveries that don't get through are tried again for a day.
API keys: for your own code and apps to look up members, payments and contacts, give access and add people to your list. A key is shown once; revoke it any time. The API reference is on the same page.