How do I make so a script only executes if a certain developer product is bought?

Here is the script I want to be executed:

wait(1)

script.Parent.Missle.Base.Anchored = true

debounce = false

script.Parent.Button.ClickDetector.MouseClick:connect(function()
	if debounce == false then
		debounce = true
		script.Parent.Button.Sound:Play()
		
		local siren = script.Parent.Button.Siren
		siren.Parent = workspace
		siren:Play()
		
		coroutine.resume(coroutine.create(function()
			local lights = script.Parent.Lights:GetChildren()
			for i=1,100 do
				for i,v in pairs(lights) do
					v.SpotLight.Enabled = true
				end
				wait(0.54)
				for i,v in pairs(lights) do
					v.SpotLight.Enabled = false
				end
				wait(0.54)			
			end
		end))
		
		wait(2)
		
		script.Parent.Missle.Base.Fire.Enabled = true
		script.Parent.Missle.Base.Smoke.Enabled = true
		
		wait(3)
		
		script.Parent.Missle.PrimaryPart = script.Parent.Missle.Base	
		for i=1,320 do
			script.Parent.Missle:SetPrimaryPartCFrame(script.Parent.Missle:GetPrimaryPartCFrame()+Vector3.new(0,0.05*((1.1^(i/5))/3),0))
			wait()
		end
		wait()
		for i=1,100 do
			script.Parent.Missle:SetPrimaryPartCFrame(script.Parent.Missle:GetPrimaryPartCFrame()+Vector3.new(0,0.05*(1.1^((250-i)/5)/3),0))
				script.Parent.Missle:SetPrimaryPartCFrame(script.Parent.Missle:GetPrimaryPartCFrame()*CFrame.Angles(0,math.pi/100,0))
				script.Parent.Missle:SetPrimaryPartCFrame(script.Parent.Missle:GetPrimaryPartCFrame()+Vector3.new(0,0,-i/100))	
			wait()
		end
		wait()
		for i=200,120,-1 do
			script.Parent.Missle:SetPrimaryPartCFrame(script.Parent.Missle:GetPrimaryPartCFrame()-Vector3.new(0,0.1*((1.1^(i/2.95))/4),0))
			wait()
		end	
		
		script.Parent.Missle.Tip.Transparency = 0.5
		script.Parent.Missle.Tip.CanCollide = false
		script.Parent.Missle.Tip.Mesh.Scale = Vector3.new(1,1,1)
		local boom = script.Parent.Button.Boom
		boom.Parent=workspace
		boom:Play()
		local frame = script.Parent.Missle.Tip.CFrame
		
		script.Parent.Missle.Tip.Boom.Disabled = false	
		
		for i=1,400 do
			script.Parent.Missle.Tip.Size=script.Parent.Missle.Tip.Size+Vector3.new(3,3,3)
			script.Parent.Missle.Tip.CFrame=frame
			wait()
		end
		script.Parent.Missle.Tip.Boom.Disabled=true
		script.Parent.Missle:Destroy()
		siren:Stop()
		boom:Stop()
		
		
	end
end)

You can do this by listening to the receipts being processed by the MarketPlaceService and checking if the purchase went well.

For example:

local MarketplaceService = game:GetService("MarketplaceService")
local Players = game:GetService("Players")
local ProductId = 000000000 -- Your Developer Product Id

local function Bought(Receipt)
	-- Your code here
	
	return true -- Indicate a successful purchase
end

local function CheckReceipt(ReceiptInfo)
	local Player = Players:GetPlayerByUserId(ReceiptInfo.UserId, ReceiptInfo)
	if Player then -- For security purposes
		if not ReceiptInfo.ProductId == ProductId then
			return -- Cancel the function early if it isn't the product you're listening for
		end
		
		local success, result = pcall(Bought)
		if success then
			return Enum.ProductPurchaseDecision.PurchaseGranted
		else
			warn("Failed to process receipt:", receiptInfo, result)
		end
	end
	
	return Enum.ProductPurchaseDecision.NotProcessedYet
end

MarketplaceService.ProcessReceipt = processReceipt

Note that I actually do not know if this script works as it should since I couldn't test it, please tell me if you have any issues with the script.