The older versions of firefox allow the used to save their tabs when they close firefox. Why don't the newer versions allow it?
hello, this is now done automatically - therefore firefox won't ask you to do that each time the browser session ends. for more information please refer to: Restore previous session - Configure when Firefox shows your most recent tabs and windows
Make sure that you do not run Firefox in (permanent) Private Browsing mode.
In case you are using "Clear history when Firefox closes":
Note that clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, and passwords.