Excel bestand als alleen lezen na bepaalde tijd

Sub TimeBombWithDefinedName()
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' TimeBombWithDefinedName
' This procedure uses a defined name to store this workbook's
' expiration date. If the expiration date has passed, a
' MsgBox is displayed and this workbook is closed.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim ExpirationDate As String

On Error Resume Next
ExpirationDate = Mid(ThisWorkbook.Names("ExpirationDate").Value, 2)
If Err.Number <> 0 Then
    '''''''''''''''''''''''''''''''''''''''''''
    ' Name doesn't exist. Create it.
    '''''''''''''''''''''''''''''''''''''''''''
    ExpirationDate = CStr(DateSerial(Year(Now), _
        Month(Now), Day(Now) + C_NUM_DAYS_UNTIL_EXPIRATION))
    ThisWorkbook.Names.Add Name:="ExpirationDate", _
        RefersTo:=Format(ExpirationDate, "short date"), _
        Visible:=False
End If

''''''''''''''''''''''''''''''''''''''''''''''''''''''
' If the today is past the expiration date, close the
' workbook. If the defined name didn't exist, we need
' to Save the workbook to save the newly created name.
''''''''''''''''''''''''''''''''''''''''''''''''''''''
If CDate(Now) > CDate(ExpirationDate) Then
    MsgBox "This workbook trial period has expired.", vbOKOnly
    ThisWorkbook.Close savechanges:=False
End If

End Sub

Private Sub Workbook_Open()
 If Date > DateValue("11-06-2017") Then
   With ThisWorkbook
        If Not .ReadOnly Then .ChangeFileAccess xlReadOnly
          .Saved = True
        End With
  End If
End Sub

Private Sub Workbook_Open()
Dim sh As Worksheet
For Each sh In Sheets
 sh.Protect "shalhevet", , , , -1
Next sh
End Sub

Option Explicit

Public origValue As String

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Date > DateValue("11-06-2017") Then
    If Target.Count = 1 Then
        origValue = Target.Formula
    End If
End If
End Sub

Private Sub Worksheet_Change(ByVal Target As Range)
If Date > DateValue("11-06-2017") Then
    If Target.Count = 1 Then
        Application.EnableEvents = False
        MsgBox "Expiratiedatum bereikt. U mag geen wijzigingen meer aanbrengen. Neem contact op met ... bla bla bla ..."
        Target.Formula = origValue
        Application.EnableEvents = True
    End If
End If
End Sub