In the past few years, we have covered plenty of plugins that let you start your own membership site and set a password for your premium content. Multiple Post Passwords for WordPress is also worth a look. It lets you set expiring passwords for your posts.
Once you activate the plugin, a box is added to your posts that lets you add multiple passwords for your posts and pages. Multiple Post Passwords lets you set an email for password deletion notifications. You can also delete used password once a day.