Using Ionic.Zip dll, Password Protected zip does not ask for password second time c#

Question

I have started with zip encryption and requirement is to password protect the files. i.e. Whenever we try to unzip the zip file, it should ask for password. Below is the code i'm using.

            using Ionic.Zip;    


            public static void ZipFilesWithPassword(string DirectoryToZip, string ZipFileToCreate)
            {
                using (ZipFile zip = new ZipFile())
                {
                    zip.Password = "pwd12345";
                    String[] filenames = System.IO.Directory.GetFiles(DirectoryToZip);
                    foreach (String filename in filenames)
                    {
                        ZipEntry e = zip.AddFile(filename, "");
                        e.Password = "pwd12345";
                    }
                    zip.Save(ZipFileToCreate);
                }
            }

It seems to be working but not every time. When i try to unzip zip file manually by using "Extract All...".. for the first time, its asking for password. But if i delete the extracted folder and try to unzip again its not asking for password. But in same case by using the 7-Zip if i try to extract the zip, its asking for the password every time.

My question is..

Is this the default behavior of Ionic.zip? Can we configure from code to ask for password, every time we unzip?