Make Your Application with Trial Version

using SecureApp;

static void Main()
{
    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    string path = @"Software\Tanmay\Protection";
    Secure scr = new Secure();
    bool logic = scr.Algorithm("tanmay", path);
    if(logic ==true)
        Application.Run(new Form1());
}

bool logic = scr.Algorithm("tanmay", path);

public bool Algorithm(String appPassword, String pass)
{
    globalPath = pass;
    bool chpass = checkPassword(appPassword);
    if (chpass == true) //execute
        return true;
    else
    {
        bool block = blackListCheck();
        if (block == false)
        {
            string chinstall = checkfirstDate();
            if (chinstall == "First")
            {
                firstTime();// installation date
                DialogResult ds = MessageBox.Show("You are using trial Pack! Would you Like to Activate it Now!", "Product key", MessageBoxButtons.YesNo, MessageBoxIcon.Information);
                if (ds == DialogResult.Yes)
                {
                    Form1 f1 = new Form1(appPassword, globalPath);
                    DialogResult ds1 = f1.ShowDialog();
                    if (ds1 == DialogResult.OK)
                        return true;
                    else
                        return false;
                }
                else
                    return true;
            }
            else
            {
                string status = dayDifPutPresent();
                if (status == "Error")
                {
                    blackList();
                    DialogResult ds = MessageBox.Show("Application Can't be loaded, Unauthorized Date Interrupt Occurred! Without activation it can't run! Would you like to activate it?", "Terminate Error-02", MessageBoxButtons.YesNo, MessageBoxIcon.Error);
                    if (ds == DialogResult.Yes)
                    {
                        Form1 f1 = new Form1(appPassword, globalPath);
                        DialogResult ds1 = f1.ShowDialog();
                        if (ds1 == DialogResult.OK)
                            return true;
                        else
                            return false;
                    }
                    else
                        return false;
                }
                else if (status == "Expired")
                {
                    DialogResult ds = MessageBox.Show("The trial version is now expired! Would you Like to Activate it Now!", "Product key", MessageBoxButtons.YesNo, MessageBoxIcon.Information);
                    if (ds == DialogResult.Yes)
                    {
                        Form1 f1 = new Form1(appPassword, globalPath);
                        DialogResult ds1 = f1.ShowDialog();
                        if (ds1 == DialogResult.OK)
                            return true;
                        else
                            return false;
                    }
                    else
                        return false;
                }
                else // execute with how many day remaining
                {
                    DialogResult ds = MessageBox.Show("You are using trial Pack, you have " + status + " days left to Activate! Would you Like to Activate it now!", "Product key", MessageBoxButtons.YesNo, MessageBoxIcon.Information);
                    if (ds == DialogResult.Yes)
                    {
                        Form1 f1 = new Form1(appPassword, globalPath);
                        DialogResult ds1 = f1.ShowDialog();
                        if (ds1 == DialogResult.OK)
                            return true;
                        else
                            return false;
                    }
                    else
                        return true;
                }
            }
        }
        else
        {
            DialogResult ds = MessageBox.Show("Application Can't be loaded, Unauthorized Date Interrupt Occurred! Without activation it can't run! Would you like to activate it?", "Terminate Error-01", MessageBoxButtons.YesNo, MessageBoxIcon.Error);
            if (ds == DialogResult.Yes)
            {
                Form1 f1 = new Form1(appPassword, globalPath);
                DialogResult ds1 = f1.ShowDialog();
                if (ds1 == DialogResult.OK)
                    return true;
                else
                    return false;
            }
            else
                return false;
            //return "BlackList";
        }
    }
}

All other methods are in source code. So download full source code if you want to use it.

Screen Shorts:

When First time it will open,

Next time,

And few days latter,

If user Want to enter Product key then chose Yes Button & the screen will be,

If user interrupt in system date the Error Message will like,

If trial Version is expired,

If enter a Correct Product key,

Other wise it looks like,

Now in every time, the original application will start first, like the sample,

Limitation

All the information is saved in Registry, so it can be found. You should create a complex path.

As Product key is in main project, for several product key you should build it for several times.

Few Words

This article just shows a sample or can say an easiest way to make trial product.

It is built in Visual Studio 2010 & framework 3.5.

That's it.

Hope, it will help you!

Thank you!