Excel vba to work on ALL workbooks


I have this code:

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)

Lastrow = ActiveSheet.Cells(Rows.Count, 12).End(xlUp).Row

If ActiveWorkbook.Name Like "FR_*" And WorksheetFunction.CountIf(ActiveSheet.Range(Cells(4, 12), Cells(Lastrow, 12)), "<>Pending Distribution") > 0 Then
MsgBox "Warning, column L has values other than Pending Distribution"
Cancel = True
End If
End Sub

It works when it is saved into the Workbook in vba but it doesn't work in Personal.xlsb

I want to make it work on ALL workbook that start with FR_

but it is not working despite I am using ActiveSheet and ActiveWorkbook, why ?