title: how to use oauth2 token permanently?
body: <p>I would like to use the oauth2 token permanently in my website.</p>
  
  <p>Using google API, when the user giving permission to manage their google calendar, I am getting the access token from google API. I want to save it in database and use it for the last long.</p>
  
  <p>But it is getting invalid. I tried to refresh the token using the oauth2 refresh token API. But getting the error as follows.</p>
  
  <blockquote>
    <p>Array ( [error] => invalid_grant [error_description] => Token has been expired or revoked. ) </p>
  </blockquote>
  
  <p>I don't want the user to give the permission each time when he enters the website.</p>
  
  <p>I would also like the admin need to access the user's calendar using this token or any other way if it is.</p>
  
  <p>How can I achieve this?</p>