C#

using System;
using System.Text;
using System.Security.Cryptography;

namespace first
{
    class MainClass
    {
        public static void Main (string[] args)
        {
            string Company = "ABCD";
            string CompanyID = "1234";
            string ActivationCode = MainClass.Formula(Company, CompanyID);
            Console.WriteLine (ActivationCode);
        }

        public static string Formula (string Company, string CompanyID)
        {
            string Md5 = EncodeString(CompanyID.Trim() + Company.Trim());
            string HexMd5 = Md5.Substring(0, 10);
            long DecMd5 = Math.Abs(long.Parse(HexMd5, System.Globalization.NumberStyles.HexNumber));
            string ActivationCode = DecMd5.ToString();
            return ActivationCode.Substring(0,7) + '-' + ActivationCode.Substring(7);
        }

        public static string EncodeString(string password)
        {
            string md5encoded;
            using (MD5 md5 = new MD5CryptoServiceProvider())
            md5encoded = BitConverter.ToString(md5.ComputeHash(Encoding.UTF8.GetBytes(password)));
            return md5encoded.Replace("-", String.Empty);
        }
    }
}