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In the case of Android and I-Phone, your collected booster is stored in the device memory.Boosters can be lost anytime for the app crashes.ย Perhaps your problem was the same in this case.
Here are some tips for not/less facing this kind of problem in the future,
Make your device software auto update.
Make your game app auto update.
Don't open game when battery below 25%
Don't accept incoming call when you playing this game.
Close all background running app before start this game.
Make free device internal memory up to 2 GB
Do not install large app on the device as these may cause game app to crash.
Keep RAM free.ย Do not install large app on the device as these may cause game app to crash.