You are excited that you heard about this game and you are loving it! You have started receiving free booster rewards from playing some events. That's great! Suddenly your game crashes and you panic - what to do? Your first reaction is to uninstall and reinstall the game. Much to your surprise, when the game reinstalls and you login to your Facebook or Kingdom account your boosters are all gone. You worked so hard to save them for difficult levels only to lose them because of a crash.
It is because of this happening to many players on mobile devices in the past, we want you to be aware of this now so that it doesn't happen to you.
note that the boosters are saved to your device and not the game data, so you
can use them when offline too. This does mean that any updates, crashes or
device changes can cause these items to be lost. For this reason, we do not
recommend storing too many of the won boosters as these can indeed be lost
unlike Gold Bars.
Management wants you to fully understand the consequences of how it can happen on a mobile device, so they have created a blog entitled "Safeguarding your collected boosters and lives" and you can read the details here