How to check if the user is authorized on the site via oAuth?

Question

API

Good evening. I'm doing oauth for the first time. I do authorization through vk. Everything is OK, returns code. Authorization passes without errors. But Now it is necessary to give access to the closed material. And if he is not authorized, then close the material that he should see after authorization.

Answer 1

So here as well as using a username and password. You create a session, only there is no password, but OK from VK.