No, it's not required – you can use the Standard version of Isadora instead.

Using a USB Key license is the fastest cross-platform option for quickly moving a license from computer to computer and is ideal for bouncing between a number of computers quickly, especially when internet access is not available. It is also ideal for academic institutions that wish to "check out" licenses to students, faculty, or staff. With an Isadora USB Key license, you can run Isadora on any computer in which the key (i.e., "dongle") is inserted. Just insert the key, start up Isadora, and you'll be able to edit and save your patches.

To learn more about the Isadora USB Key licensing system, please read this support article titled: "How does USB Key licensing system work?"