Hi Randy,
Thanks for getting in touch — glad to see you’re considering Events Calendar PRO for your project and I hope it’s a great fit!
The plugin will absolutely continue to work after the year-long license is up. You simply lose access to future plugin updates or access to the support forums here on our site.
That said, I do want to note that our plugins work best together when they are all running the same version. For example, if you are running The Events Calendar 4.4.4 (latest), then you will want to run Events Calendar PRO 4.4 or above as well. Otherwise, you will likely notice functional differences or incompatibilities. In other words, I would suggest not updating The Events Calendar after your Events Calendar PRO license expires to ensure compatibility.
Does this help answer your question? Please let me know.
Cheers!
Geoff