Magic Kicker - 3 User License
Prevent Multiple People Logging Into a Single Account

Features

• Block Sharing Login Info
• Flexible Settings
• Timed Lockouts
• Lockout & Logout Feature
• Record Login IP
• Display Access Logs

Unlimited License is for unlimited hosts (unlimited domains and sub domains)
Magick Kicker is a stand alone plugin which you can use on any Wordpress site.