Hi, Jess. Thanks for your interest in our plugin suite.
You only need to buy the Multisite Level license for a product if you’ll be using it on more than 10 sub-sites on your network because our Agency Level license allows that many.
Therefore, if you’ll be using Filter Bar on just 1 of your sub-sites, you could buy the Personal Level license for Filter Bar even if you have the Multisite Level license for Events Calendar PRO.
The one caveat is that a non-Multisite Level license in use on a network won’t receive automatic updates, but you can always get the latest version at https://theeventscalendar.com/my-account/downloads/
Last but not least, we have Bundles and a pretty great Refund Policy so you can buy one or many of our add-ons and thoroughly test them.
I hope this info helps. Let me know if you have any follow-up questions.