.htaccess and passwd protection

helloo

i'm starting to learn to play with the .htaccess file and just protected one of many directories on one of my sites with it.

But there is one thing i wonder; once you type in the username and password to get access to the directory, its like, there is no logout option.
If i leave the directory and then come back afterwards, it doesnt prompt me for the password anymore.

So, do i have to create php sessions with the .htaccess file? For how much time the door will stay open?

What's the best use of the .htaccess in a passwd protection circumstance?

Thanks