MapViewer hosted in a WPF
App.xaml.cs
// Copyright 2010 ESRI
// 
// All rights reserved under the copyright laws of the United States
// and applicable international laws, treaties, and conventions.
// 
// You may freely redistribute and use this sample code, with or
// without modification, provided you include the original copyright
// notice and use restrictions.
// 
// See the use restrictions.
// 

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Windows;
using ESRI.ArcGIS.esriSystem;

namespace WPFMapViewer
{
  /// <summary>
  /// Interaction logic for App.xaml
  /// </summary>
  public partial class App: Application
  {
    protected override void OnStartup (StartupEventArgs e)
    {
      base.OnStartup (e);

      ESRI.ArcGIS.RuntimeManager.Bind(ESRI.ArcGIS.ProductCode.Engine);
      InitializeEngineLicense ();
    }

    private void InitializeEngineLicense ()
    {
      AoInitialize aoi = new AoInitializeClass ();

      //more license choices could be included here
      esriLicenseProductCode productCode = esriLicenseProductCode.esriLicenseProductCodeEngine;
      if (aoi.IsProductCodeAvailable (productCode) == esriLicenseStatus.esriLicenseAvailable)
      {
        aoi.Initialize (productCode);
      }
    }
  }
}