Never seen a need to pay for premium thought.
I only wish it would do more that just mark tasks as completed. Ideally is would represent that with dates laps time & some type of visualisation of how much you've accomplished per day, week or month. Linking that to journaling would be even better. But so far it's the best to do list app I've explored.
Curious to see what others are finding.
Hope it will helpful for you
Sometimes a piece of paper could be the best, a notebook or a fancy app, though is not about the app but the discipline you put into it.