Why wouldn't my Messaging System work after player leaves?

This is the Script so if a player click's so from the whole server people can make and see Part's but it would disconnect and lose all the parts that spawn it will disconnect but i didn't put Connection:Disconnect when the player leaves and also when an player joins a new server it dosen't show the parts that are called from other servers before it only shows the new parts who are called after the player joins and people call from the same server or different server?

I don't know how to fix these please help.

local MessagingService = game:GetService("MessagingService")
local Click = game.Workspace.Part.ClickDetector
local success,errormessage = pcall(function()
	
	MessagingService:SubscribeAsync("Global",function(msg)
		local Part = Instance.new("Part",game.Workspace)
		Part.Name = "Start"
	end)
end)
wait(2)
local success,errormessage = pcall(function()
	Click.MouseClick:Connect(function()
			MessagingService:PublishAsync("Global","part")
	end)
end)