There are two editions of DayPilot:
1. DayPilot Lite (Open-Source) - available under Apache License 2.0
DayPilot Lite for ASP.NET: http://www.daypilot.org/daypilot-lite/
DayPilot Lite for MVC: http://mvc.daypilot.org/lite/
DayPilot Lite for JavaScript: http://javascript.daypilot.org/lite/
DayPilot.Modal is also open-source:
https://code.daypilot.org/81367/daypilot-modal
2. DayPilot Pro (commercial)
This is a paid version with additional features.
You can check the availability of individual features in the documentation:
https://doc.daypilot.org
There is an "Availability" table at the bottom of each feature page where you can check the editions.
See also the feature matrix (Lite vs Pro) for the JavaScript version:
http://javascript.daypilot.org/feature-matrix/