How To Create and Add a Game Server Login Token (GSLT) to your Counter Strike Global Offensive (CS GO) Server:
Due to Valve's new policies on plugins for CSGO servers (weapon paints, knife plugins) They have introduced a new system that requires each user to link their steam account to their CSGO Server. You must complete this step in order for your server to be fully operational:
First of all head on over to the signup page:
http://steamcommunity.com/dev/managegameservers
Scroll towards the bottom, towards the two input boxes.
Enter the APP ID for csgo (730) in the first input and you can type a note in the second, e.g. gameserver1 or matchserver1
When you attempt to add this for the first time you may get an error (see below) if you have not added your phone number to your steam account:

If you encounter this error then please add your phone number to your account via this url:
https://store.steampowered.com/phone/add
Once you have completed this step you may repeat the first step to regenerate a GSLT token for your server:
After you have added the app id 730 and your comment you will see your new token below in a table
You can now copy and paste the Login Token into the Control Panel or add:
sv_setsteamaccount TOKEN
To your autoexec.cfg file inside the cfg folder
After adding the token to the control panel click Save "Configuration & Restart"