bool execute = false;
double versLokal = 0;
versLokal = Convert.ToDouble(this.keyfield.Text);
string tempVersInfo = "C:\Windows\keys.txt"
string pathVersInfoServ = "http://meinspace.de/keys.txt"


	wc.DownloadFile(pathVersInfoServ, tempVersInfo);
            TextReader tr = new StreamReader(tempVersInfo);
           
            int NumberOfLines = 15;
                        string[] ListLines = new string[NumberOfLines];
				  for (int i = 1; i < NumberOfLines; i++)
            {
                ListLines[i] = tr.ReadLine();
                
                double  verstest = Convert.ToDouble(ListLines[i]);
                if(versLokal == verstest)
                {
                	execute = true;
                break;
                }
            }

[WebMethod]
bool CheckKey(String key){}

/*
 * using System.Net;
 * using System.IO;
 */

bool execute = false;
double versLokal = Convert.ToDouble(this.keyfield.Text);
string pathVersInfoServ = "http://meinspace.de/keys.txt";

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(pathVersInfoServ);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.Default);
while(!sr.EndOfStream) {
    if(versLokal == Convert.ToDouble(sr.ReadLine()))
    {
        execute = true;
        break;
    }
}
sr.Close();
response.Close();

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;

public class URLTunnel
{
    /// <summary>
    /// Liest den Inhalt einer URL ein und gibt ihn aus
    /// </summary>
    /// <param name="url">Adresse</param>
    /// <returns>String Eingelesene Adresse</returns>
    public static string PostGetURL(string url)
    {
        return PostGetURL(url, "");
    }

    /// <summary>
    /// Schickt Daten per POST an eine URL, liest ihren Inhalt ein und gibt ihn aus
    /// </summary>
    /// <param name="url">Adresse</param>
    /// <param name="postData">Daten in Form: key=value&key2=value2...</param>
    /// <returns>String Eingelesene Adresse</returns>
    public static string PostGetURL(string url, string postData)
    {
        try
        {

            WebRequest request = WebRequest.Create(url);

            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";

            if (postData != "")
                StreamToWebRequest(request, postData);

            WebResponse webResponse = request.GetResponse();

            StreamReader sr = new StreamReader(webResponse.GetResponseStream(), Encoding.Default);
            return sr.ReadToEnd();
        }
        catch (Exception e)
        {
            return e.Message;
        }
    }

    /// <summary>
    /// Sendet Daten an eine URL
    /// </summary>
    /// <param name="request">Verweis auf ein WebRequest</param>
    /// <param name="data">Daten, die gesendet werden sollen</param>
    private static void StreamToWebRequest(WebRequest request, string data)
    {
        byte[] bytes = null;
        bytes = System.Text.Encoding.Default.GetBytes(data);
        request.ContentLength = bytes.Length;
        Stream outputStream = request.GetRequestStream();

        outputStream.Write(bytes, 0, bytes.Length);

        outputStream.Close();
    }
}

/* Hier ein Beispiel für den Aufruf der Klasse */
public Form1 : Form
{
    public Form1() {
        string check = Convert.ToBoolean( URLTunnel.PostGetURL("http://meinspace.de/check_key.php", "key=" + textBox.Text) );
        if(check)
            MessageBox.Show("Key gültig.");
    }

        
}

  bool check = Convert.ToBoolean( URLTunnel.PostGetURL("http://meinspace.de/check_keys.php", "key="+this.keyfield.Text) );
        if(check)
        {
            MessageBox.Show("Key gültig.");
            execute = true;
        }
        else
        {
          MessageBox.Show("Key ungültig.");
          execute = false;
        }

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(pathVersInfoServ);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.Default);
while(!sr.EndOfStream) {
    if(versLokal == Convert.ToDouble(sr.ReadLine()))
    {
        execute = true;
        break;
    }
   
}
sr.Close();
response.Close();

System.IO.Streamreader does not contain a definition for EndOfStream (CS0117)