Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        End
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim intTime As Integer = 1
        Dim dteLastStart, dteStartDate As Date
        Dim blnFirstTime, blnEnabled As Boolean
        Dim lngTimeLeft As Long

        blnEnabled = True
        If dteStartDate = Nothing Then
            dteStartDate = Now
        End If

        My.Application.SaveMySettingsOnExit = True

        If DateDiff(DateInterval.Day, dteLastStart, Now) < 0 Then
            'First clock change
            If intTime = 1 Then
                MsgBox("This software has detected that you have changed your system date to an earlier date" & vbCrLf _
                & "As this softwaer has built-in security," & vbCrLf _
                & "this software will only run until the next intTime you change your system date", _
                MsgBoxStyle.OkOnly Or MsgBoxStyle.Exclamation, "System Date Changed")
                intTime = 2
            ElseIf intTime = 2 Then
                'Second clock change
                blnEnabled = False
                MsgBox("This software has detected that you have changed your system date to an earlier date" & vbCrLf _
                & "As this is the second warning, this software will now be disabled", _
                MsgBoxStyle.OkOnly Or MsgBoxStyle.Exclamation, "System Date Changed")
            End If
            'disables app
            If blnEnabled = False Then
                If MsgBox("Software is disabled", MsgBoxStyle.OkOnly Or MsgBoxStyle.Information, "Disabled") = MsgBoxResult.Ok Then
                    For Each form As Form In My.Application.OpenForms
                        form.Close()
                    Next
                End If
            End If
        End If
        If DateDiff(DateInterval.Day, dteStartDate, Now) > 15 Then
            blnEnabled = False
            If blnEnabled = False Then
                If MsgBox("This software has reached the end of it's trial.", MsgBoxStyle.OkOnly Or MsgBoxStyle.Information, "Trial Ended") = MsgBoxResult.Ok Then
                    'Close all open forms
                    For Each form As Form In My.Application.OpenForms
                        form.Close()
                    Next
                End If
            End If
        End If
        dteLastStart = Now
        If blnFirstTime = True Then
            blnFirstTime = False
        End If
        'Saves variable settings
        My.Settings.Save()

        lngTimeLeft = 15 - (DateDiff(DateInterval.Day, dteStartDate, Now))

        MsgBox("This software is a trial version and can only be used for 15 days." _
        & "If you would like to purchase this software please contact DMB Software for the full version" & vbCrLf _
        & "You have " & CStr(lngTimeLeft) & " days left.", _
        MsgBoxStyle.OkOnly, "Software Trial")

    End Sub
End Class