Counting users logins on separate devices

I have a an application like many others where users are able to login to their account.
I have sessions stored in the database and everything is working smoothly.

I realized that how the sessions work by default, under one user account, that user can technically log in to their account from many locations or devices at the same time. I know this because I can provide support by logging in as the user while they are logged in somewhere else.

Knowing this, I was looking to figure a way out to monetize this by limiting this login count somehow and if a user wanted to log in with more than X amount of different locations on the same username/password account they would have to pay. Does anybody know how this would be possible?