App.xaml.cs

using System.IO;
using System.Reflection;
using System.Text;
using System.Windows;

namespace AppearanceCustomization
{
    /// <summary>
    /// Interaction logic for App.xaml
    /// </summary>
    public partial class App : Application
    {
        public App()
        {
            Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense(FindLicenseKey());
        }

        /// <summary>
        /// Helper method to find a syncfusion license key from the Common folder
        /// </summary>
        /// <returns></returns>
        public static string FindLicenseKey()
        {
            int levelsToCheck = 12;
            string filePath = @"Common\SyncfusionLicense.txt";

            string rootPath = System.IO.Path.GetDirectoryName(Assembly.GetEntryAssembly().CodeBase.Replace(@"file:///", ""));

            for (int n = 0; n < levelsToCheck; n++)
            {
                string fileDataPath = System.IO.Path.Combine(rootPath, filePath);
                if (System.IO.File.Exists(fileDataPath))
                    return File.ReadAllText(fileDataPath, Encoding.UTF8);
                DirectoryInfo rootDirectory = Directory.GetParent(rootPath);
                if (rootDirectory == null)
                    break;
                rootPath = rootDirectory.FullName;

            }
            return string.Empty;
        }
    }
}