Dev Products example

local buyButton = script.Parent.Button.Button
local productId = ID
local Plr = script.Parent.Parent

buyButton.MouseButton1Click:connect(function()
    Game:GetService("MarketplaceService"):PromptProductPurchase(Plr, productId)
end)

local MarketplaceService = Game:GetService("MarketplaceService")

MarketplaceService.PromptProductPurchaseFinished:connect(function(userId, productId, isPurchased)
if isPurchased then
--What happens after purchase
end
end)

local buyButton2 = script.Parent.Button2.Button
local productId2 = ID

buyButton2.MouseButton1Click:connect(function()
    Game:GetService("MarketplaceService"):PromptProductPurchase(Plr, productId2)
end)

MarketplaceService.PromptProductPurchaseFinished:connect(function(userId, productId2, isPurchased2)
if isPurchased2 then
--What happens after purchase
end
end)