Nope, you can add multiple subscriptions to the same suretyDIY website login. Each location requires its own Alarm.com account, and each Alarm.com account will require its own unique username. However, you can connect the accounts with Multi-System Access after they are created so that you can access them all with the same credentials and swap between them within the app.
If you have existing compatible equipment and unregistered communication module, you would just need to purchase a subscription for each.
Do you have existing equipment or are you looking for new systems?