Yes. While the base subscription supports two devices on the same platform (like an Android phone and and Android tablet, for instance), the Multi-Platform upgrade is required to support...well, multiple platforms.
From the Annual Subscription page in the store (https://www.iflygps.com/STORE/Product...ta-subscription):
Quote:Do you have more than 2 devices or need to run across different platforms? Select the "
Multi-Platform Upgrade" option! Then you can share this subscription across 4 iPads/iPhones, Android phones and tablets, Windows devices and iFly Aviation Portables The base subscription supports up to two devices on one platform.