"Licence" an excel spreadsheet

A simple thing would be to close the workbook if the windows logon doesn't match, something like this

Private Sub Workbook_BeforeClose(Cancel As Boolean)
Dim sh As Worksheet
Sheets("Welcome").Visible = xlSheetVisible
For Each sh In Sheets
sh.Visible = xlSheetVeryHidden
Next sh
End Sub
 
Private Sub Workbook_Open()
Dim sh As Worksheet
If Environ("username") <> "Simon" Then
Application.Quit
Else
For Each sh In Sheets
sh.Visible = xlSheetVisible
Next sh
Sheets("Welcome").Visible = xlSheetHidden
End If
End Sub

Don't forget to create a Welcome sheet, and the code goes in the ThisWorkbook module.