Yes, it is free. You can use it for free indefinitely, and it will not suddenly become unusable or require payment after a certain number of days.
For those who want to hide ads, use all theme colors, or set wallpapers and date background colors freely, we also offer the paid "Premium service". However, for regular use, there is no problem, and you can continue using it for free, so please rest assured.
* If you previously purchased the one-time "Remove ads" option, you can keep using the app without ads at no extra cost.