Roblox DataStore

local DataStoreService = game:GetService("DataStoreService")
local myDataStore = DataStoreService:GetDataStore("MyDataStore")

game.Players.PlayerAdded:Connect(function(player)

    local leaderstats = Instance.new("Folder", player)
    leaderstats.Name = "leaderstats"

    local cash = Instance.new("IntValue", leaderstats)
    cash.Name = "Cash"


    local playerUserId = "Player_"..player.UserId

    -- Load data

    local data
    local success, errormessage = pcall(function()
        data = myDataStore:GetAsync(playerUserId)
    end)

    if success then
        cash.Value = data
        -- Set our data equal to the current cash
    end
end)

game.Players.PlayerRemoving:Connect(function(player)
    local playerUserId = "Player_"..player.UserId

    local data = player.leaderstats.Cash.Value

    local success, errormessage = pcall(function()
        myDataStore:SetAsync(playerUserId, data)
    end)

    if success then
        print("Successfully saved!")
    else
        print("There was an error!")
        warn(errormessage)
    end

    myDataStore:SetAsync(playerUserId, data)
end)