How To Add Stud Distance To A Script?

So here is a script that enables the player to click and drag a unioned part. What is necessary to add to this to make sure players are not able to drag the part from a certain distance?

plr = game.Players.LocalPlayer
mouse = plr:GetMouse()
target = {}

script.Parent = game.StarterPlayer.StarterPlayerScripts
function click()
	if mouse.Target then
		if mouse.Target:IsA("UnionOperation") and mouse.Target.Locked == false then
			target.part = mouse.Target
			target.anchored = target.part.Anchored
			target.part.Anchored = true
			dim = true
			mouse.Move:connect(function()
				
				if dim then
					target.part.CFrame = CFrame.new(
						mouse.Hit.X,target.part.CFrame.Y,mouse.Hit.Z)
				elseif not dim then
				end
				
			end
			)
			mouse.Button1Up:connect(function()
				dim = false
				 target.part.Anchored = target.anchored
				
			end)
		end
	end
end
mouse.Button1Down:connect(click)

In the properties of the Click Detector, you should see " Max Activation Distance. You can change it.