CodeScript

local DataStore = game:GetService("DataStoreService"):GetDataStore("Codes")

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

    local key = "codes-"..player.userId

    local folder = Instance.new("Folder", player)
    folder.Name = "Codes"
    local save = DataStore:GetAsync(key)

    if save then
        for i = 1,#save do
            local saved = Instance.new("BoolValue", folder)
            saved.Name = save[i]
        end
    end
end)

game.ReplicatedStorage.Code.OnServerEvent:Connect(function(player, reward ,code)
    local key = "codes-"..player.userId
    local currency = player.leaderstats:FindFirstChild("Cash")
    currency.Value = currency.Value + reward

    local bool = Instance.new("BoolValue", player.Codes)
    bool.Name = code
    bool.Value = true

    local activated = {}

    for i,v in pairs(player.Codes:GetChildren()) do
        if v:isA("BoolValue") then
            table.insert(activated, v.Name)
            DataStore:SetAsync(key, activated)
        end
    end
end)