Sub GetHDD_SerNum()
    Set objWMIService = GetObject("winmgmts:\\.\root\cimv2")
    Set colItems = objWMIService.ExecQuery("SELECT * FROM Win32_DiskDrive", , 48)
    For Each Item In colItems
        MsgBox Item.SerialNumber
    Next
End Sub

Private Declare Function GetVolumeInformation Lib "Kernel32" Alias "GetVolumeInformationA" (ByVal lpRootPathName As String, ByVal lpVolumeNameBuffer As String, ByVal nVolumeNameSize As Long, lpVolumeSerialNumber As Long, lpMaximumComponentLength As Long, lpFileSystemFlags As Long, ByVal lpFileSystemNameBuffer As String, ByVal nFileSystemNameSize As Long) As Long

Private Const Original_Vol_SN = 1032938

Private Sub Check_SerNum()
    Dim Vol_SN As Long
    Dim DrvPath As String
    DrvPath = Left(Application.Path, 3) ' смотрим откуда запустили нашу программу
    GetVolumeInformation DrvPath, vbNullString, 0, Vol_SN, 0, 0, vbNullString, 0
    If Vol_SN <> Original_Vol_SN Then
        MsgBox "Вы, мерзкие пиратишки, украли мою гениальную программу!", vbCritical
    End If
End Sub