As I understand, if you buy in the App Store you can specify up to 5 family members who can use your purchase on their (Apple) devices. I don't know yet, if the licensing rules for purchases directly from Serif apply when installing an App Store purchased Software on a non-Apple PC?
Licence from Serif states every device "that you personally own or control." Theortically, I could control every device in my household, even if I don't know the password. Is it meant this way?
So this would set a Serif-purchase (nearly) on par with an App Store-purchase, but with more money for the developer. I guess, that Serif is very generous with this license – as long, as the software is not used commercially by members of your household.