Alot. Which is a shame because the app used to be decent a little over a decade ago. I remember using it back in highschool before the gamification and, without paying, it would let you access community forums, review lessons, and a lot of other features now locked behind a paywall or gone entirely.

I still remember when the heart system was first introduced and getting pissed that i had to essentially get everything right to keep moving forward in the lesson or pay to refill my hearts. I uninstalled when it became 3 wrong answers and youre done for the day without payment.