public static void RememberThatTheKeyAlmostExpiredMessageWasDisplayedToday()
 {
     RegistryHelpers.SaveSetting("KeyAlmostExpiredMessageLastDisplayDate", DateTime.Today.ToOADate().ToString(CultureInfo.InvariantCulture));
 }
 public static void SetValidityLimit(string featureId, DateTime validityLimit)
 {
     RegistryHelpers.SaveSetting("Validity_" + featureId, validityLimit.ToOADate().ToString(CultureInfo.InvariantCulture));
 }