The "now" parameter has been formatted as "yyyy-MM-dd HH:mm:ss".
The licensing depends on whether you're using FullCalendar Standard or FullCalendar Premium.
https://fullcalendar.io/license
Fixed event.extendedProps object to be used as json.
Added RRule plugin:
The RRule plugin is a connector to the rrule js library. It is powerful for specifying recurring events, more so than FullCalendar’s built-in simple event recurrence.