Yes, it is free.
You can use it free of charge for as long as you like. It will never suddenly stop working after a few days or start requiring payment.
For users who want additional features, we offer a paid plan called "Premium Service".
With Premium, ads are hidden, and you also get unlimited use of all theme colors and fonts, wallpaper settings and date background colors, every new feature added in the future, and priority support.
Even without Premium, the basic features such as adding and checking events remain free to use. Please rest assured.