title: Limit number of concurrent sessions per user using IdentityServer4
body: <p>We have a couple of users which we might are sharing their user account with other users. We are thinking on adding functionality within IdentityServer4 which limits the number of concurrent sessions a user can have to prevent this behaviour.</p>
  
  <p>This won't prevent the users from sharing user accounts from time to time during the day, but we will at least be able to stop concurrent use of our systems.</p>
  
  <p>We are thinking on counting the number of refresh tokens used by each user account and if they exceeds a certain limit, the oldest refresh tokens and access tokens are deleted for that user, this until the amount of refresh tokens is equal the allowed limit.</p>
  
  <p>Any input on how this functionality can be implemented using IdentityServer4? We would also like to inform the user why the reference token was deleted therefore causing an log-off.</p>