Like other mentioned JetBrain has a very good Model. I also like the model of Agenda: https://agenda.community/t/get-all-features/21 https://agenda.community/t

Like other mentioned JetBrain has a very good Model. I also like the model of Agenda: https://agenda.community/t/get-all-features/21 https://agenda.community/t/get-all-features/21 "Agenda comes out of the box with a great set of features, completely free. There are no time or trial limits. You can use it forever, at no cost. Agenda does offer extra premium features that require an In App Purchase, and that make the app even more powerful. If you decide to purchase the upgrade, you permanently unlock all current premium features across all of your devices. Each of them is described in detail below. Additionally, any new premium features we add in the 12 months following your purchase are also permanently unlocked."