title: How to expire a access token in ouath2
body: <p>I have currently came across OAuth2 , and I found it quite interesting, so I decided to use it in my application. The question that I face when implementing it were</p>
  
  <ol>
  <li>should I use a database to save and lookup access token and see if they're expired </li>
  <li>what could be the possible data model for it</li>
  <li>if not, how can I expire an access token that already been issued</li>
  </ol>
  
  <p>I'll appreciate any help </p>