NotifyPlus is not like other schedulers offering a similar feature. Those programs are usually loaded with other features you don't want and they have to stay in memory all the time to work. NotifyPlus is designed to check on events just at Windows startup time, reminds you if there is an event and then unloads itself from memory. Sure, you are only reminded when you start Windows but for the usually events like anniversaries isn't that enough?
You can setup NotifyPlus to remind you of any upcoming yearly, monthly, weekly or once-only event up to 15 days ahead. So if your Mom's birthday is next week you will be reminded any time you start Windows starting 15 days before that day if you like. Besides of the German and English language support another feature added in a previous version is the notification of passed events since the last check.