Stay Logged In Permanently?

Sessions are files / DB records... stored server side.

They are pieces of information (like your user ID and other key info) grouped and identified by a unique ID stored in your browser cookies.

When your browser connects to the site, this ID, if it was present in your browser, is sent along with the connection request and checked, server side, against the server ones. If there is a match, the server concludes it's you and you're automatically logged in.

But these sessions are small pieces of information stored somewhere and totally inactive when you are not connected. A big site like chess.com doesn't need worry about the space that takes.

When you connect to play, on the other hand, the server has to maintain active TCP connections with your browser. This is what is costly, resource wise.

In conclusion, sessions are not really a concern.

They probably did some changes that killed the login "Remember" feature. The session cookie being of the "session" type, it dies when the browser is closed (it's browser dependent, it might be kept alive for a bit longer).

There's ten million+ active accounts a day. Session checking uses resources and adds up over a lot of records, so it isn't minor. Staff posted in this topic about it as well.

I'm pretty confident they didn't just forget something and the behavior is by design.

Just started happening to me as well. The "remember me" option is not working and I have to type in my credentials every time I visit the site instead of being automatically logged on. Super annoying bug, I hope they fix it asap.

Yes.
Didn't want to keep feeding a lengthy technical discussion (basically that tiny amount of "trigger" data (session) is nothing even with millions of users and has nothing to do with the current problem).

All big sites ensure users can log back in using complementary cookies or a different session cookie type. It's easy, trivial. And that doesn't affect performance in any way. The session cookie is used when the user navigates through the site, and when they've been away for some time, they're logged back in automatically. It's not using an active session per say. All big sites do that.

It's a bug. They use a PHP session cookie that dies along with the browser and their mechanism to log a user back automatically is broken. The "Remember" checkbox does not even work anymore.

Didn't do anything in particular but it's back to normal for me!

"Remember me" is an elementary feature that any beginner web developer should be able to implement, and it doesn't produce any extra server load.
This site is a complete joke.