Detecting when a player steps off of a part

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#1

I have a tool shop, and when you get within a certain radius (represented by an invisible part), a GUI will appear to prompt you to enter the shop. However, I can’t figure out how to remove the GUI once the player is not longer on top of that part. I’ve tried .TouchedEnded, but it works in very strange ways while on top of the part.

#2

using magnitude would be the easiest way to do this
localscript in startercharacterscripts

task.wait(2)
local ShopPart = workspace.ShopPart --// change this 
local Root = script.Parent:WaitForChild("HumanoidRootPart")

while true and task.wait(0.1) do 
	if (Root.Position - ShopPart.Position).Magnitude <= 12 then --// 12 is the radius in studs from the part then
        --// show the ui
	else 
		--// hide the ui
	end
end