"there is a developer product at the top of the screen what says Random event when you buy it a random event will happen you will get 200 walkspeed of 1000 jumppower or death the developer product id is 1556140163"

-- local script (StarterGUI) 
local player = game.Players.LocalPlayer
local screenGui = Instance.new("ScreenGui", player.PlayerGui)

local devProductId = 1556140163

local devProductButton = Instance.new("TextButton", screenGui)
devProductButton.Text = "Random Event"
devProductButton.TextColor3 = Color3.fromRGB(255, 255, 255)
devProductButton.BackgroundColor3 = Color3.fromRGB(0, 0, 0)
devProductButton.UICorner = 5
devProductButton.AnchorPoint = Vector2.new(0.5, 0)
devProductButton.Position = UDim2.new(0.5, 0, 0, 0)

local function onDevProductPurchase()
    local randomEvent = math.random(1, 3)

if randomEvent == 1 then
        -- 200 walkspeed 
        player.Character.Humanoid.WalkSpeed = 200
    elseif randomEvent == 2 then
        -- 1000 jumppower 
        player.Character.Humanoid.JumpPower = 1000
    else
        -- death 
        player.Character.Humanoid.Health = 0
    end
end

devProductButton.MouseButton1Click:Connect(function()
    game:GetService("MarketplaceService"):PromptProductPurchase(player, devProductId)
end)

game:GetService("MarketplaceService").PromptProductPurchaseFinished:Connect(function(playerWhoBought, productId, wasPurchased)
    if playerWhoBought == player and productId == devProductId and wasPurchased then
        onDevProductPurchase()
    end
end)