c#实现软件注册

http://www.cnblogs.com/ynbt/archive/2011/11/02/2233470.html

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32;

namespace SoftRegister
{
    public partial class frmMainForm : Form
    {
        public frmMainForm()
        {
            InitializeComponent();
        }
        SoftReg softReg = new SoftReg();
        private void btnClose_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void btnReg_Click(object sender, EventArgs e)
        {
            frmRegisterForm frmRegister = new frmRegisterForm();
            frmRegister.ShowDialog();
        }

        ///<summary>
        /// 窗体加载
        ///</summary>
        ///<param name="sender"></param>
        ///<param name="e"></param>
        private void frmMainForm_Load(object sender, EventArgs e)
        {
            //判断软件是否注册
            RegistryKey retkey = Registry.CurrentUser.OpenSubKey("SOFTWARE", true).CreateSubKey("wxf").CreateSubKey("wxf.INI");
            foreach (string strRNum in retkey.GetSubKeyNames())
            {
                if (strRNum == softReg.GetRNum())
                {
                    this.lblRegInfo.Text = "此软件已注册！";
                    this.btnReg.Enabled = false;
                    return;
                }
            }
            this.Text = "此软件尚未注册！";
            this.btnReg.Enabled = true;
            MessageBox.Show("您现在使用的是试用版，可以免费试用30次！","信息",MessageBoxButtons.OK,MessageBoxIcon.Information);
            Int32 tLong;
            try
            {
                 tLong= (Int32)Registry.GetValue("HKEY_LOCAL_MACHINE\SOFTWARE\Angel", "UseTimes", 0);
                MessageBox.Show("您已经使用了" + tLong + "次！", "信息", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            catch 
            {
                MessageBox.Show("欢迎使用本软件！","信息",MessageBoxButtons.OK,MessageBoxIcon.Information);
                Registry.SetValue("HKEY_LOCAL_MACHINE\SOFTWARE\Angel","UseTimes",0,RegistryValueKind.DWord);
            }
            tLong = (Int32)Registry.GetValue("HKEY_LOCAL_MACHINE\SOFTWARE\Angel", "UseTimes", 0);
            if (tLong < 30)
            {
                int tTimes = tLong + 1;
                Registry.SetValue("HKEY_LOCAL_MACHINE\SOFTWARE\Angel", "UseTimes", tTimes);
            }
            else 
            {
                DialogResult result = MessageBox.Show("试用次数已到！您是否需要注册？", "信息", MessageBoxButtons.YesNo, MessageBoxIcon.Information);
                if (result == DialogResult.Yes)
                {
                    frmRegisterForm.state = false;
                    btnReg_Click(sender, e);
                }
                else 
                {
                    Application.Exit();
                }
            }
        }
    }
}