Sub RegistroUsuario()
'Macro para gravar o usuário que abriu a planilha

Dim GetUserN
Dim ObjNetwork
Set ObjNetwork = CreateObject("WScript.Network")
GetUserN = ObjNetwork.UserName

If Worksheets("Plan1").Range("BZ1") = "" Then
    Worksheets("Plan1").Range("BZ1").FormulaR1C1 = GetUserN
    Worksheets("Plan1").Range("CA1").FormulaR1C1 = Now
Else
    lastrow = Worksheets("Plan1").Cells(Rows.Count, 78).End(xlUp).Row + 1
    Worksheets("Plan1").Range("BZ" & lastrow).FormulaR1C1 = GetUserN
    Worksheets("Plan1").Range("CA" & lastrow).FormulaR1C1 = Now
End If
End Sub

Sub AUTO_OPEN()
    RegistroUsuario
End Sub

Sub AUTO_CLOSE()
    ActiveWorkbook.Save
End Sub