AivarasFX

Plugin creates widget that displays simple horizontal login. 
If theme has registered sidebar on top, widget may be used to display Horizontal login for top of the page for webpage users.
Input boxes are aligned in horizontal way, not verticaly. For blog users there is no need to open wordpress login page to login.
If blog has WP-fb-autoconnect plugin installed, widget also displays Facebook connect button and allows users to connect using facebook credentials.

FX simple LoginLogout

Plugin displays simple horizontal login for top of the page. If WP-fb-autoconnect plugin installed users may connect using facebook credentials

Duck Dev

Joel James

Loggedin is a lightweight WordPress plugin that lets you easily limit the number of simultaneous active sessions a user can have. This is a crucial feature for membership sites, online courses, and other platforms where you need to prevent users from sharing their accounts.
<h3>🎁 Features</h3>
<ul>
<li>Set Global Limits: Define a maximum number of concurrent logins for all users.</li>
<li>Flexible Login Behavior: Choose to either block new logins when the limit is reached or automatically log out the oldest session to allow a new one.</li>
<li>Prevent Account Sharing: By limiting sessions, you can effectively stop users from sharing their login credentials with others.</li>
<li>Admin Control: Easily force log out a user from the admin dashboard, giving you full control over active sessions.</li>
<li>Developer-Friendly: The plugin is built with a hook-based architecture, making it highly customizable and extensible for developers.</li>
</ul>
<h3>📦 Addons</h3>
Enhance LoggedIn’s functionality with these simple yet powerful <a href="https://duckdev.com/addons/loggedin/" rel="nofollow ugc">add-ons</a>.
<ul>
<li>
<a href="https://duckdev.com/addon/limit-per-user/" rel="nofollow ugc">Limit Per User</a>: For more granular control, the Limit Per User addon allows you to set specific login limits for individual users, overriding the global settings. This is perfect for offering different tiers of access or special privileges.
</li>
<li>
<a href="https://duckdev.com/addon/real-time-logout/" rel="nofollow ugc">Real-time Logout</a>: This add-on ensures a truly seamless experience by checking for logouts in real time. When a user’s session is terminated in the background due to a login limit, the add-on will automatically refresh their page, instantly restricting access.
</li>
</ul>
<h3>🐛 Bug Reports</h3>
Found a bug? We welcome your bug reports! Please report any issues directly on the <a href="https://github.com/Joel-James/loggedin/issues" rel="nofollow ugc">Loggedin GitHub repository</a>.
Please note: GitHub is for bug reports and development-related issues only. For support, please use the WordPress.org support forums.

Loggedin – Limit Concurrent Sessions

Good Plugin

Good

Lightweight plugin that limits an account to a specific number of concurrent logins.

FX simple LoginLogout vs Loggedin – Limit Concurrent Sessions