Below is the code I use for a Pop Up box when the value of a cell is
greater than a certain number. I only want this Pop Up box to show up
once. I need the code to be modified for that to happen. Will someone
assist me with that?

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
Dim rng As Range
Dim rng2 As Range


Set rng = Range("b37") '<<==== CHANGE to suit


On Error Resume Next
Set rng2 = rng.Precedents
If rng2 Is Nothing Then Set rng2 = rng
Set rng2 = Intersect(rng2, Target)
On Error GoTo 0


If Not rng2 Is Nothing Then
If rng.Value 500 Then
Application.EnableEvents = False
MsgBox "Local Manager Approval Required"
Range("c37").Value = "Local Manager Approved (amount over
$500.00)"
Application.EnableEvents = True
End If
End If
End Sub