set date in settings or registry

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C#

How would I set the date in the registry after installation and extract the date to see if it has expired after 30 days?

Here is my code:
Any better way to this as well?

/// <summary>
          /// The main entry point for the application.
          /// </summary>
          [STAThread]
          static void Main()
          {
               string dateInString = "04.10.2011"; //this date will be extracted from the registry when program was installed
               DateTime startDate = DateTime.Parse(dateInString);
               DateTime expiryDate = startDate.AddDays(30);
               if (DateTime.Now > expiryDate)
               {
                    DialogResult LicenseAgreement = MessageBox.Show("Do you acknowledge the EULA?" + "\n This message will appear every 30 days",
                    "End User License Agreement",
                    MessageBoxButtons.YesNo,
                    MessageBoxIcon.Question,
                    MessageBoxDefaultButton.Button2);

                    if (LicenseAgreement == DialogResult.No)
                    {
                         MessageBox.Show("The program will exit now then");
                         Application.ExitThread();

                    }
                    else
                    {
                         RunProgram run = new RunProgram();
                    }
               }
               else
               {
                    RunProgram run = new RunProgram();
               }            
          }
          private class RunProgram
          {
               public RunProgram()
               {
                    Application.EnableVisualStyles();
                    Application.SetCompatibleTextRenderingDefault(false);
                    Application.Run(new Form1());
               }
          }
          
     }