Decrypt date using md5

See more:

C#

WinForms

dear experts ;
i try to create win form project to encrypt some data string , int and date to generate license for my project
i need to decrypt date field to check if license expired or not every login
or if open sours available to generate lic with (customer name , project name , max users ,expiry date and server key ) info it'll be better

What I have tried:

encyrpt code
static string key { get; set; } = "A!9HHhi%XjjYY4YP2@Nob009X";
        public static string Encrypt(string text)
        {
            using (var md5 = new MD5CryptoServiceProvider())
            {
                using (var tdes = new TripleDESCryptoServiceProvider())
                {
                    tdes.Key = md5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
                    tdes.Mode = CipherMode.ECB;
                    tdes.Padding = PaddingMode.PKCS7;

                    using (var transform = tdes.CreateEncryptor())
                    {
                        byte[] textBytes = UTF8Encoding.UTF8.GetBytes(text);
                        byte[] bytes = transform.TransformFinalBlock(textBytes, 0, textBytes.Length);
                        return Convert.ToBase64String(bytes, 0, bytes.Length);
                    }
                }
            }
        }