Developer products; output error "Studio API access is not enabled"?

Does that mean that my game must have save features in order to use developer products?

My script is located inside of a StartMenu Gui, and localscript.

Player = game.Players.LocalPlayer
Menu = script.Parent
Play = Menu.Play
Pack1 = Menu.Pack1
Pack2 = Menu.Pack2

function PlayGame()
    Menu:remove()
end
Play.MouseButton1Down:connect(PlayGame)

function Buy1()
    --LocalScript in StarterPack
-- setup local variables
local buyButton = Pack1
local productId = 20518668

-- when player clicks on buy brick prompt him/her to buy a product
buyButton.MouseButton1Click:connect(function()
    game:GetService("MarketplaceService"):PromptProductPurchase(game.Players.LocalPlayer, productId)
end)




--Script in BuyButton part
-- setup local variables
local MarketplaceService = Game:GetService("MarketplaceService")
local ds = game:GetService("DataStoreService"):GetDataStore("PurchaseHistory")
local productId = 32819339

-- define function that will be called when purchase finished
MarketplaceService.ProcessReceipt = function(receiptInfo) 

    -- find the player based on the PlayerId in receiptInfo
    for i, player in ipairs(game.Players:GetChildren()) do
        if player.userId == receiptInfo.PlayerId then


            -- check which product was purchased
            if receiptInfo.ProductId == productId then

                -- handle purchase
                player.leaderstats.Money.Value = player.leaderstats.Cash.Value + 1000000
            end
        end
    end 

    -- record the transaction in a Data Store
    local playerProductKey = "player_" .. receiptInfo.PlayerId .. "_purchase_" .. receiptInfo.ProductId
    ds:IncrementAsync(playerProductKey, 1)  

    -- tell ROBLOX that we have successfully handled the transaction
    return Enum.ProductPurchaseDecision.PurchaseGranted     
end
end
Pack1.MouseButton1Down:connect(Buy1)