Hi Giuseppe,
Thanks for checking out our plugins! You are correct that the Events Calendar Pro license costs $89 per year, which entitles you to plugin updates as well as premium support in our help desk. Once the license expires, you will need to renew it to continue to have access to updates and support, but the plugin will not stop working on your site. However, it is important to note that if you continue to update WordPress and your theme and other plugins, you may eventually start to run into compatibility issues if you do not also update Events Calendar Pro.
Please let me know if you have any other questions!
Thanks,
Jennifer