Accessory Giver GUI if player HasPass, how to?

Local Script

local Market = game:GetService("MarketplaceService")
local Remote = game:GetService("ReplicatedStorage"):WaitForChild("AttachHat")
local Player = game.Players.LocalPlayer

local ButtonGui = script.Parent
local Gui = ButtonGui.Parent:WaitForChild("HatGui")

ButtonGui.TextButton.Activated:Connect(function()
	if Market:UserOwnsGamePassAsync(Player.UserId, 5949403) then
		Gui.Enabled = true
		ButtonGui.Enabled = false
	else
		Gui.Enabled = false
		ButtonGui.Enabled = true
	end
end)

for i, v in pairs(Gui:GetDescendants()) do
	if v:IsA("ImageButton") then
		v.Activated:Connect(function()
			Remote:FireServer(v.Name)
		end)
	end
end

Server Script

local Remote = Instance.new("RemoteEvent")
Remote.Name = "AttachHat"
Remote.Parent = game:GetService("ReplicatedStorage")

Remote.OnServerEvent:Connect(function(Player, Button)
	for i, v in pairs(Player.Characer:GetDescendants()) do
		if v:IsA("Accessory") then
			v:Destroy()
		end
	end
	
	local newaccessory = Instance.new("Accessory")
	newaccessory.Parent = Player.Character
	
	local newhandle = Instance.new("Part")
	newhandle.Parent = newaccessory
	newhandle.Size = Vector3.new(1, 1, 1)
	newhandle.CanCollide = false
	newhandle.Anchored = false
	
	local newmesh = Instance.new("SpecialMesh")
	newmesh.Parent = newhandle
	newmesh.Scale = Vector3.new(1, 1, 1)
	
	local newweld = Instance.new("Weld")
	newweld.Part1 = Player.Character:WaitForChild("Head")
	newweld.Part0 = newhandle
	
	if Button == "Button1" then
		newweld.C0 = CFrame.new(0, 0, 0)
		newmesh.MeshId = "http://www.roblox.com/asset/?id=0"
		newmesh.TextureId = "http://www.roblox.com/asset/?id=0"
	end
end)

UserOwnsGamePassAsync is used to get the GamepassId, UserHassPass is deprecated

You need to use Remote Events (one is created in the Server Script for you) in order to communicate between the Server and the Client

In this example, there are two ScreenGuis (one for the button to open the hat gui) Place your TextButton / LocalScript into the "ButtonGui" and the ImageButtons into the "HatGui"

If you add Frames, make sure to account for these in the definitions of Gui and ButtonGui

The thing to edit for each button is to make sure that the name of the button matches a string as shown by if (Button = "Button1" then) then alter the offset (c0) and mesh / texture accordingly.

Make sure the Hat Gui "Enabled" property is disabled first