How to make my 'sessions' to never expire?

I'm using Zend Framework.

I want to do something similar to SO, when you are not a registered user开发者_JS百科, you keep your account as long as you remove all your cookies.

I know that session <> cookies, however what will be the best way to do that?

By the way, I'm using memcached because I plan to share sessions between frontend.

Is there any recommendations about this? because memcached data are volatile.

May I need to store them in a database instead?

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A possible solution could be calling Zend_Session::rememberMe() in each request, once you have checked that the user is authenticated.

Hope that helps,