The open source license is designed for you to use Infinite Scroll to build
open source and personal projects. The Infinite Scroll open source license is
GPLv3. The GPLv3 has many terms, but the most important is how it is sticky
when you distribute your work publicly. From the GPL FAQ:

If you release the modified version to the public in some way, the GPL
requires you to make the modified source code available to the program's
users, under the GPL.

Releasing your project that uses Infinite Scroll under the GPLv3, in turn,
requires your project to be licensed under the GPLv3. If you are okay with
this, feel free to use Infinite Scroll under the GPLv3, without purchasing
a commercial license.