Subscription and usage help, please:)

Hi!

We're opening Norway's largest Makerspace (the only real, unaffiliated one), and we really like the Appointments+ plugin for WP.
I haven't been able to find a simple answer on your website about the how stuff actually works.
I've signed up for a free trial, and we're wondering- if we subscribe fully, and use the plugin- will we retain functionality if we end our subscription?
Is this basically a subscription-based plugin, or can we use it as we please?
Thanks!