Check Application Expiry Date

                               Check And Set Expiry Date For Application

Every client asking for assigning expiry date for his application because of security policy and

protection scheme,programmer have different way to do this.

        1.Use a two-way hash to store the initial date and compare that to the present date. 

           You can save the hash to disk.

        2.Use the registry key of current user and set the key value at installation time and compare
           to change the value in particular Date. 

        3.Use the created date of your installation files as a reference.

        4.Create a license key that encodes the expiry date into the key and read this when the

           application runs.

Well here i write a small code for checking expire date to the application,with the help of Date and

Registry feature- 

Imports Microsoft.Win32

Imports System.IO.Directory

Imports Microsoft.VisualBasic.DateAndTime

Public Class ThisWorkbook

    Private Function checkExpired()

        Dim RS232RegKey As RegistryKey

        Dim pluginExpired As Boolean = False

         If Year(Now) > 2013 Or Year(Now) < 2013 Then

             pluginExpired = True

         End If

         If Month(Now) > 4 Or Month(Now) < 4 Then

             pluginExpired = True

         End If

        If Day(Now) > 16 Or Day(Now) < 13 Then

             pluginExpired = True

         End If

        RS232RegKey = Registry.CurrentUser.CreateSubKey("Software\Microsoft\Office\Excel\Addins\RS232")

        RS232RegKey = Registry.CurrentUser.OpenSubKey("Software\Microsoft\Office\Excel\Addins\RS232", True)

         If RS232RegKey.GetValue("PluginExpired") Is Nothing Then

             RS232RegKey.SetValue("PluginExpired", 1, RegistryValueKind.DWord)

         End If

         If pluginExpired = True Then

             RS232RegKey.SetValue("PluginExpired", 0, RegistryValueKind.DWord)

         End If

        Dim PluginExpiredRegVal As Integer = RS232RegKey.GetValue("PluginExpired")

        RS232RegKey.Close()

         If pluginExpired = True Or PluginExpiredRegVal = 0 Then

             MsgBox("Plugin Expired")

             Return True

         End If

         Return False

    End Function

    Private Sub ThisWorkbook_Startup() Handles Me.Startup

        Globals.Sheet2.ButtonStop.Enabled = False

        If (checkExpired()) Then

            Globals.ThisWorkbook.Save()

            Globals.ThisWorkbook.Close()

        End If

    End Sub    

End Class