Access to Registry Key Denied

namespace Thermocoders_Licensing_System
{
    class TrialTimeManager
    {
        private string temp = "";

        public TrialTimeManager() { }

        public void SetNewDate()
        {
            DateTime newDate = DateTime.Now.AddDays(31);
            temp = newDate.ToLongDateString();
            StoreDate(temp);
        }

        public void Expired()
        {
            string d = "";
            using (Microsoft.Win32.RegistryKey key = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(@"SOFTWARE\MyApp"))
            {
                d = (String)key.GetValue("Date");
            }
            DateTime now = DateTime.Parse(d);
            int day = (now.Subtract(DateTime.Now)).Days;
            if (day > 30) { }
            else if (0 < day && day <= 30)
            {
                string daysLeft = string.Format("{0} days more to expire", now.Subtract(DateTime.Now).Days);
                MessageBox.Show(daysLeft);
                
            }
            else if (day <= 0)
            {
                MessageBox.Show("Trial Expired Please Purchase The Product");
            }
        }

        public void StoreDate(string value)
        {
            try
            {
                using (Microsoft.Win32.RegistryKey key = Microsoft.Win32.Registry.LocalMachine.CreateSubKey(@"SOFTWARE\MyApp"))
                {
                    key.SetValue("Date", value, Microsoft.Win32.RegistryValueKind.String);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        
        }

    }

}