Refer a friend and get free plus is fraud and does not work. Use the desktop version; it doesn't have any hearts yet. Just Duolingo's luck that I have three adblockers installed there. But you reap what you sow when you try to screw over your whole userbase... Edit: the app now forces new keyboards onto me without the option to turn it off. Frankly, I'm considering uninstalling. It just gets worse and worse. Even with ad block it's the most annoying app out there