With Jamf Now, you get three free devices for life. If you want to add more than three devices, you will be asked to input your payment information. Here is guide on how to add/change your billing information.
1. In Jamf Now, click on your name in the upper right corner,
2. Click on the Profile in the drop down menu.
3.On the Account page, click on Add Credit Card.
4. Once you have completed entering your billing information, click on the green Save Payment on the bottom of the window.