Recently, Steam has changed their server hosting requirements so that steam-accounts must be linked to an online CSGO server via a token.
This token allows your server to change IPs / ports without affecting the end user.
e.g. If your server IP:PORT changes, the server will be updated on everyone's Server Browser "Favourites Tab".
For you to do create a token, you will need to do a few things in order to comply with these requirements laid out by Valve.
Once you have done this, you will see a "Login Token" has been created with the App ID + Memo you have entered in.
Go to our Game Panel, and click on the "manage" button for your server.
Once you are in the "management" page of your server:
Once you have done these 2 steps, you are now compliant with the new CSGO server requirements laid out by valve.
Keep in mind that if you have multiple servers, you will need to create a new token for each server that you own.