private void AddEntitlement(string SKU)
    {
        if (!entitlements.Contains(SKU))
        {
            entitlements.Add(SKU);

            AMN_PlayerData.AddNewSKU(SKU);
        }
    }
    //--------------------------------------
    // INITIALIZE
    //--------------------------------------

    void Start()
    {
        entitlements = AMN_PlayerData.GetAvailableSKUs();

        DisableButtons();

        SA_AmazonBillingManager.Instance.OnGetUserDataReceived                += OnGetUserDataReceived;
        SA_AmazonBillingManager.Instance.OnPurchaseProductReceived            += OnPurchaseProductReceived;
        SA_AmazonBillingManager.Instance.OnGetProductDataReceived             += OnGetProductDataReceived;
        SA_AmazonBillingManager.Instance.OnGetPurchaseProductsUpdatesReceived += OnGetPurchaseProductsUpdatesReceived;
    }