On the App I can buy a extra heart. Lately it is gone when I return the next time. It does not happen every time, but very often. I am absolutely sure I have not used it. Can anyone tell me why, this happens?
The hearts are not supported on the web version any more. So, I suppose, if after buying the heart refill, you log into the web version, it will vanish and the lingots refunded to your account.