This is not a complicated app, is just an easy way to save all your significant data in your device, for example:

When you have to do something?
Pay something?
Any interview?
Any birthday?
Any party?
Pick someone?
....
and whatever issue you think.

You can repeat it, if it occurs yearly,and also if you don't remember something, you can search it easily.

Just try it, because it is something really interesting, like a personal notebook.