Checks if a user is using a family-shared copy of Garry's Mod from an account which is banned and then kicks them

account-sharing.lua

-- This goes in:
--      lua/autorun/account-sharing.lua

-- Original post http://facepunch.com/showthread.php?t=1341204&p=43469693&viewfull=1#post43469693
-- Credit to McSimp
-- Updated to use ply:OwnerSteamID64 by BadgerCode

local function CheckFamilySharing(ply)
    -- If the player is being shared the game, this will be the other account's steam ID
    -- Otherwise, it will be the player's own steam ID
    local lenderSteamID = util.SteamIDFrom64(ply:OwnerSteamID64())

    local chatMessage = string.format("FamilySharing: %s (%s) has been lent Garry's Mod by %s", ply:Nick(), ply:SteamID(), lenderSteamID)
    print(chatMessage)

    if not (ULib and ULib.bans) then return end

    local playerIsBanned = ULib.bans[lenderSteamID]
    if playerIsBanned then
        local banMessage = string.format("%s (%s) has been lent Garry's Mod by a banned account- %s", ply:Nick(), ply:SteamID(), lenderSteamID)
        for i, ply in ipairs(player.GetHumans()) do
            ply:ChatPrint(banMessage)
        end

        ply:Kick("The account that lent you Garry's Mod is banned on this server")
    end
end

hook.Remove("PlayerAuthed", "CheckFamilySharing")
hook.Add("PlayerAuthed", "CheckFamilySharing", CheckFamilySharing)

This no longer works as Valve have removed the API endpoint
https://developer.valvesoftware.com/w/index.php?title=Steam_Web_API&type=revision&diff=238804&oldid=230181

IsPlayingSharedGame

This could be re-written to use the newer, in-game method to retrieve this information
https://wiki.facepunch.com/gmod/Player:OwnerSteamID64

Updated to use Player:OwnerSteamID64