Make A Trial Version Problem

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VB

I m make a Trial version app Some Problem

I Use This code vb.net

Public Class Trial

    Private Sub Trial_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If My.Settings.Reg = False Then

        End If

        If My.Settings.Reg = True Then
            ' Login.Show()
            'Me.Close()
        End If
        Label3.Text = Date.Now.Date.ToString
        If My.Settings.Exdate = Nothing Then
            My.Settings.Exdate = DateTime.Now.AddDays(30)
        End If
        Label4.Text = My.Settings.Exdate.Date
    End Sub

    Public Sub ResfreshTime()
        Label3.Text = DateTime.Now.Date.ToString

    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

        ResfreshTime()
 
        If DateTime.Now <> My.Settings.Exdate Then
            Label5.Text = "Your Trial Period Has Expired"
            Button1.Enabled = False
            Timer1.Stop()

        End If

    End Sub

    Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

            Login.Show()
            Me.Close()


    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

        Dim Serial As String
        Serial = InputBox("Enter Your Protuct Key", "Activate The License", 1234, , )
        If Serial = "1234" Then
            My.Settings.Save()
            My.Settings.Reg = True

            Login.Show()
            Me.Close()
        Else
            MsgBox("Product Key Is Not Valid")


        End If
    End Sub
End Class

When I change my computer date 30++ Day This Trial Version Ok then
Exm.. 11-6-2015 to 11-7-2015 Trial
Change 12-7-2015 Show "Your Trial Period Has Expired" then
When 11-6-2015 Show app ok
I want to <> DateTime.Now Show "Your Trial Period Has Expired"
When Product Key Is Valid
show label 29,28,27 etc.........Chang Date

Any body Help me........ This Problem Salved

or

How to make a Strong Trial Version VB.NET, or C# Or Java