You can install and activate Circle² on up to 3 machines at one time.
Login and then click on the Activation Codes tab to view your activation slots:
If there are more Machine ID slots filled than expected - do not fret!
When you update your OS, reformat your computer, restore from backup, etc., your computer will make a new Machine ID which can take an additional slot. It's normal and you can message support anytime you need your code reset 🙂