An active device refers to the platform on which you use pCloud Pass, e.g., Windows, Android, iOS, etc. As a free user, you can have 1 active session for 1 platform. Let's say you use pCloud Pass on an Android device.
Free users, however, are allowed 1 free active device switch every 30 days. If we go back to our example, case 2, you'll be able to switch your active device to Windows. After that, you won't be able to switch between platforms for free in the next 30 days.
Premium users can use pCloud Pass on an unlimited number of devices without interruptions.