I use a mod called "TCs Auto Rewards" for my server shop plus as a currency and when you open it as an admin it shows every player that have joined your server with the his username and the steamID . Its really useful and its a light mod so you can use it only for you just by locking or hiding the engram so your players can't craft it and use it.
If you need help with the mod just ask me, i hope that helps.
