Systems can be executed anywhere. You don’t need a subscription service for a software that saves you data in a proprietary format in order to keep a todo list, or a bullet journal or a set of notes. You don’t need the official Bullet Journal notebook to do bullet journaling: any scrap of paper and writing apparatus will do.

Likewise with tasks on your computer. If some software is actively trying to lock you into their way way of doing things, run as fast as you can in the opposite direction and take your data with you. Choose software that works with plain text and open formats.