Option Explicit
  
Private Const c_MENUBUTTON_NAME = "Testanzeige"

Public Sub Auto_Open()
  'Startroutine des Add-In:
  ' 1) Menu-Eintrag erstellen
  Dim myMenuBar As Office.CommandBarPopup
  Dim myMenuButton As Office.CommandBarButton
  On Error Resume Next
  'Im Hauptmenue 'Extras' finden
  Set myMenuBar = Application.CommandBars(1).FindControl(, 30007)
  'Button anfügen
  Set myMenuButton = myMenuBar.Controls.Add(msoControlButton)
  'Button benennen
  myMenuButton.Caption = c_MENUBUTTON_NAME
  myMenuButton.BeginGroup = True
  'Button mit Hauptprogramm verknüpfen
  myMenuButton.OnAction = ThisWorkbook.Name & "!" & "Testanzeige"
  Set myMenuButton = Nothing: Set myMenuBar = Nothing
  On Error GoTo 0
End Sub

Public Sub Auto_Close()
  'Enderoutine des Add-In:
  ' 1) Menu-Eintrag löschen
  Dim myMenuBar As Office.CommandBarPopup  
  On Error Resume Next
  'Im Hauptmenue 'Extras' finden
  Set myMenuBar = Application.CommandBars(1).FindControl(, 30007)
  'Button löschen
  myMenuBar.Controls(c_MENUBUTTON_NAME).Delete
  Set myMenuBar = Nothing
  On Error GoTo 0
End Sub

Public Sub Testanzeige()
End Sub