System.Security.Cryptography.X509Certificates.X509Certificate.GetExpirationDateString C# (CSharp) Method

        public virtual string GetExpirationDateString()
        {
            return GetNotAfter().ToString();
        }

        public bool isActiveLicense(string license)
        {
            bool response = false;

            try
            {
                System.Security.Cryptography.X509Certificates.X509Certificate certtmp = new System.Security.Cryptography.X509Certificates.X509Certificate(license);
                System.DateTime a        = new System.DateTime(1, 1, 1, 0, 0, 0);
                System.DateTime fromDate = System.Convert.ToDateTime(certtmp.GetEffectiveDateString());
                if (fromDate == a)
                {
                    System.Threading.Thread.Sleep(1000);
                    fromDate = System.Convert.ToDateTime(certtmp.GetEffectiveDateString());
                }
                System.DateTime toDate = System.Convert.ToDateTime(certtmp.GetExpirationDateString());
                if (toDate == a)
                {
                    System.Threading.Thread.Sleep(1000);
                    toDate = System.Convert.ToDateTime(certtmp.GetEffectiveDateString());
                }
                int result  = System.DateTime.Compare(fromDate, System.DateTime.Now);
                int result2 = System.DateTime.Compare(System.DateTime.Now, toDate);
                if (result <= 0 && result2 <= 0)
                {
                    response = true;
                }
            }
            catch (System.Security.Cryptography.CryptographicException)
            {
            }
            return(response);
        }