Hi John,
Good question. Events Calendar PRO actually works alongside The Events Calendar, so both are installed and running at the same time. You’re current events will be safe and sound when you install and activate Events Calendar PRO, assuming you keep The Events Calendar active while you do it. 🙂
As a side note, if you are installed Events Calendar PRO 4.2.2.1, then I would encourage you to make sure The Events Calendar is also running version 4.2.2 to ensure full compatibility.
Does this help answer your question? Please let me know.
Cheers!
Geoff