How to create license key for a software developed in c#.net?

using System;
using System.Security.Cryptography;
using System.Text;
namespace LicenseKeyGenerator
{
class Licence
{
static void Main(string[] args)
{
string productName = "MyModuleName";
string clientIdentificationId = "webeduclick.com";
string versionNumber = "01.00.00";
string productIdentifier = (productName + "-" + clientIdentificationId + "-" + versionNumber).ToLower();
Console.WriteLine(string.Format("Product Identifier: {0}", productIdentifier));
Console.WriteLine(string.Format("Unformatted License Key: {0}", GetMd5Sum(productIdentifier)));
Console.WriteLine(string.Format("License Key: {0}", FormatLicenseKey(GetMd5Sum(productIdentifier))));
Console.ReadLine();
}
static string GenerateLicenseKey(string productIdentifier)
{
return FormatLicenseKey(GetMd5Sum(productIdentifier));
}
static string GetMd5Sum(string productIdentifier)
{
System.Text.Encoder enc = System.Text.Encoding.Unicode.GetEncoder();
byte[] unicodeText = new byte[productIdentifier.Length * 2];
enc.GetBytes(productIdentifier.ToCharArray(), 0, productIdentifier.Length, unicodeText, 0, true);
MD5 md5 = new MD5CryptoServiceProvider();
byte[] result = md5.ComputeHash(unicodeText);
StringBuilder sb = new StringBuilder();
for (int i = 0; i < result.Length; i++)
{
sb.Append(result[i].ToString("X2"));
}
return sb.ToString();
}
static string FormatLicenseKey(string productIdentifier)
{
productIdentifier = productIdentifier.Substring(0, 28).ToUpper();
char[] serialArray = productIdentifier.ToCharArray();
StringBuilder licenseKey = new StringBuilder();
int j = 0;
for (int i = 0; i < 28; i++)
{
for (j = i; j < 4 + i; j++)
{
licenseKey.Append(serialArray[j]);
}
if (j == 28)
{
break;
}
else
{
i = (j) - 1;
licenseKey.Append("-");
}
}
return licenseKey.ToString();
}
}
}