--Heres an example for saving and loading data

local dss=game:GetService("DataStoreService"):GetDataStore("Lol")

function onJoined(player)
   local key="user_"..player.UserId
   local credits=Instance.new("StringValue", player)
   credits.Name="Credits"
   credits.Value=dss:GetAsync(key) or 0
end

function onLeft(player)
   local key="user_"..player.UserId
   local success, message=pcall(function()
      dss:SetAsync(key, player.Credits.Value)
   end)
   if success then
      print("Saved " .. player.Name .. " data")
   else
      print("Failed to save " ..player.Name .. " data." ..message)
   end
end

game.Players.ChildAdded:Connect(function(player) onJoined(player) end)
game.Players.ChildRemoved:Connect(function(player) onLeft(player) end)