Every free user account is given 1 free manga download slot for iOS version, or 3 free slots for Android version. Premium user account has unlimited slots
You can choose to earn more rocks and use them to unlock more slots (20 rocks / extra manga)
OR you can Upgrade to Premium Account for unlimited slot.
You will not lose rocks for downloading within your available download slots, or re-downloading any manga you once downloaded before.
You can keep track of your rock purchase and usage in Rock History in Manage Account section.
For iOS: Open Account tab > Advanced Settings > Storage used
For Android: Open the icon > click on icon > Storage used
You can customize a feature to prevent unintentional loss of mobile data:
Open the icon > click on icon > Personalize > Switch ON Download only with Wi-Fi
Open the icon > click on icon > Personalize > Switch ON Increase number of connections with Wi-Fi
This feature enables you to download up to 4 chapters concurrently instead of just 2 chapters.
Reduce data usage
For Android: Open the icon > click on icon > Personalize > Switch ON Reduce data usage
Delete read chapters
For iOS: Open manga viewer > Tap on Settings icon > Advanced Settings > Switch ON Delete read chapters
For Android: Open manga viewer > Tap on Settings icon > Advanced > Switch ON Delete read chapters