How to read mac address of system

System.Management.ManagementClass mc = default(System.Management.ManagementClass);
ManagementObject mo = default(ManagementObject);
mc = new ManagementClass("Win32_NetworkAdapterConfiguration");

ManagementObjectCollection moc = mc.GetInstances();
    foreach (var mo in moc) {
        if (mo.Item("IPEnabled") == true) {
              Adapter.Items.Add("MAC " + mo.Item("MacAddress").ToString());
         }
     }

 using System;


namespace expireApp 
{
  public class expire
  {   
    private double _daysSelect;
    private string _dateInstall;
    private TimeSpan _daysRemaining;
    private string errors = "NONE";
    private string _evaluationVersion = "OFF";        
    private DateTime dateInstalled;
    private DateTime dateEnd;    
    private bool status;
          
    public double daysSelect 
    { 
      set 
      { 
        _daysSelect = value; 
      } 
    }

    public string dateInstall 
    { 
      set 
      { 
        _dateInstall = value; 
      }                    
    }
                 
    public bool expireStatus
    {
      get 
      {   
        compareDate();
        return(status);  
      }  
    }

    public string errorStatus
    {
      get
      {
        errorCheck();
        return(errors);
      }
    }
         
    public double daysRemaining
    {
      get
      {
        _daysRemaining = dateEnd.Subtract(getCurrentDate());  
        return(_daysRemaining.TotalDays + 1);
      }
    }
    
    private void errorCheck()
    {
      if (_evaluationVersion != "ON" && _evaluationVersion != "OFF" && _evaluationVersion == "")
      {
        errors = "_evaluationVersion Tag is not properly set!!!";
      }
      if (_evaluationVersion == "OFF")
      {
        errors = "_evaluationVersion Tag property is set to OFF";
      }
      if (_daysSelect == 0)
      {
        errors = "Expiration days cannot be zero or empty !!!";
      }
      if (_dateInstall == "")
      {
        errors = "Installation date is empty or null value !!!";
      }

    }
    
    private void start()
    {
      if (_evaluationVersion == "ON")
      {        
        if (_daysSelect != 0 && _dateInstall != "" )
        {
          parseTheDate(_dateInstall);
          getDateEnd();          
        } 
        else 
        {  
          errorCheck();  
        }
      }
      else if (_evaluationVersion == "OFF") 
      {
        errorCheck();
      }      
                        
    }
    
    public string evaluationVersion 
    { 
      set 
      { 
        _evaluationVersion = value;
        start(); 
      } 
    }
    
    private void parseTheDate(string localdate)
    {
      try 
      {
        dateInstalled = DateTime.Parse(localdate);       
      }
      catch(Exception e)
      {
        errors = e.ToString();
      }
    }    
         
    // retun the current date  
    private DateTime getCurrentDate()
    {
      return(DateTime.Today);
    }
         
    // compare the dates
    private void compareDate() 
    {    

      DateTime dateExpire;
      DateTime dateCurrent;
      bool checkStatus = false;
   
      dateExpire = dateEnd;
      dateCurrent = getCurrentDate();
     
      if (dateCurrent <= dateExpire) 
      {
        checkStatus = true;
      } 
 
      if (dateCurrent < dateInstalled) 
      {
        checkStatus = false;
      }
      
      if (dateCurrent > dateExpire) 
      {
        checkStatus = false;
      }
       
      status = checkStatus;
    }
      
    // find the last date      
    private void getDateEnd()
    {
      double i = 0;
      DateTime dateLast;
             
      dateLast = dateInstalled.AddDays(i);
             
      while (i < _daysSelect) 
      {
        dateLast = dateInstalled.AddDays(i);
        i += 1;
      }                   
         
      dateEnd = dateLast;
    }
        
  } // class expire ends here


  class Test
  { 
       static void Main()
       {       
             expire exp = new expire();
             
            exp.daysSelect = 30;           
             exp.dateInstall = "05/13/2002"; 
             exp.evaluationVersion = "ON";
               
             bool status = false;
             status = exp.expireStatus;
         
             if (status == true)
             {
               Console.WriteLine(exp.daysRemaining + " day(s) remaining " );
             }
             else if (status == false)
             {
               Console.WriteLine("Evaluation copy is expired!!!");        
             }
                          
             Console.WriteLine("Error : " + exp.errorStatus);
             
       }

  }//Test class
  
}//namespace expireApp