How many devices can I log into at once with my account?

You can leave yourself logged in on up to 5 devices in any combination of mobile and desktop while your membership is active.  

Remember that your account logs all of your skipped tracks (removing them from your bank) and records your productivity data. Account activity teaches the how service to work best for your needs, so be careful logging in on a device that is shared with others as this can affect how the service works for you.