as far as i can read this is their (affinity software) take on your question:
How many computers can I install a digital product on?
Serif Software is platform specific. If you wish to use Serif Software on both Mac and Windows platforms, you must purchase a license for each.
As a private individual, you can download, install, use and run for personal use, one copy of the Serif Software directly on each computer running either (depending on your purchased license) Microsoft Windows (“Windows Computer”) or macOS (“Mac Computer”) that you personally own or control.
As a commercial enterprise, you can download, install, use and run one copy of the Serif Software for use either: (a) by one specific individual on each of the Windows Computer(s) or Mac Computer(s) (depending on your purchased license) that they use, own or control, or (b) by multiple individuals on a single shared Windows Computer Mac Computer(s) (depending on your purchased license) that you own or control.
An End User License Agreement (EULA) is offered to the user for acceptance on product installation and can be read here.
