Continue Code

if (textBox1.Text == new WebClient().DownloadString("rawpastebinlink") || textBox1.Text == "what evere you want the key to be")
            {
                MessageBox.Show("Thank You For Using XarkkzSploit!");
                this.Hide();
                Form2 main = new Form2();
                main.Show();
            }
            else
            {
                MessageBox.Show("Incorrect Key");
            }

Get Key Code:

Process.Start("linkavert link");