To instruct the server to not update the value of a custom data field, set the value to null.
Example
// license is an instance of a QlmLicense object. When using the LicenseValidator class, // you should use licenseValidator.QlmLicenseObject.try{QlmAnalytics analytics =newQlmAnalytics(license);string errorMessage;string installID =analytics.ReadInstallID(out errorMessage);analytics.UpdateInstallEx(installID, version,analytics.GetOperatingSystem(),Environment.MachineName, computerID, activationKey,this.computerKey,license.IsEvaluation(),license.ProductName,license.MajorVersion,license.MinorVersion,"My Custom Data1",null,null );}catch (Exception ex){Console.WriteLine(ex.Message);}