laceous

Due to lack of interest (both my own and based on the number of downloads) this plugin will not be updated for WP 3.0
WordPress’ auth cookies include a built-in expiration date (either 2 or 14 days depending on if the ‘Remember Me’ option is checked). Even if you remove the client-side cookie (by manually logging out or just closing your browser if ‘Remember Me’ wasn’t checked when logging in) the data that was stored within the cookie is still valid until the expiration date is reached.
This could be an issue if someone managed to “steal” your cookie(s). They would still be able to access your website for some time into the future.
This plugin will immediately invalidate your auth cookies when you manually log out. This, of course, also means that you have to manually click ‘Log out’ for this plugin to work properly (you can’t just close your browser to remove any cookies that expire at the end of the session). This won’t prevent session hijacking, but should limit the amount of time that an attacker can access your website.

Invalidate Logged Out Cookies

This plugin will immediately invalidate your auth cookies when you manually log out.

codersantosh

AcmeIT

AddonsPress

Yam B Chhetri

This plugin limits login to one device at a time for a user. 
If the same user login from another device, that user won’t be allowed to log in. 
Admin can set up an ‘Already login message’ for that user.
If the user has been inactive for too long, then the user is automatically logged out and that user allows to log in again either from the same device or another device. 
Admin can set up ‘Auto Logout Duration’ for users.
It tracks the user’s activity like user status ( Active/Inactive ) and Last active time. 
Admin can view user status from WP Admin > Users > All users. From the “User Status” column, the user current status can be viewed.
Admin can set up only one device login limit plugin from WP Admin > Settings > Limit login
Note: This plugin is compatible with most of the membership plugins. 
If you find any issues, please use <a href="https://wordpress.org/support/plugin/only-one-device-login-limit" rel="ugc">support forum</a> to report.

Only one device login limit

Very useful plugin for security purposes



works like a charm

Limit login to one device at a time for a user. Configured options from the admin

Invalidate Logged Out Cookies vs Only one device login limit