how symfony2 remember me work without any table for token?

Question

I configure symfony2 to add remember me functionality, but how it work without any table in database to save remember me token. I mean some best practice for remember me cookie like what is said in here

Answer 1

It stores the username and the token expiration together with the token class name and the signature in the single cookie.

Here is where it's being processed: https://github.com/symfony/symfony/blob/2.8/src/Symfony/Component/Security/Http/RememberMe/TokenBasedRememberMeServices.php#L39

So the whole protection is based on using the secret token (the one you specify in parameters) and user's password.

Answering the second part of your "question" - as soon as a pure cookie-based solution does not use persistence layer, none of those "best practices" are applicable here.

symfony2 does provide built-in persistence layer support for storing remember-me tokens, and it does implement the series-based logic like it's explained in the answer you're referring to.