In reply to Sybre Waaijer.

You’re right, trialware is not permitted in the WordPress.org plugin directory. Software as a Service, however, is:
https://developer.wordpress.org/plugins/wordpress-org/detailed-plugin-guidelines/#6-software-as-a-service-is-permitted

Jetpack currently ships with 4 paid blocks. All 4 of them rely on a third-party service that lives on WordPress.com. Don’t hesitate to check them out to learn more about them:

– Recurring Payments Block
– Simple Payments Block
– Video Block
– Ad Block