This add-on allows you to send a reminder to your users and/or user roles when a post, page, or custom post type hasn’t been updated after a set amount of time. You can set this time to be in hours, days, weeks, or months.
It also allows you to send a transactional reminder notification if a user hasn’t logged in after a set amount of time.
This add-on is useful if you run a site that requires users to update content on a regular basis. For example, if you run an educational institute, you might require that students update their homework or lab note posts on a daily or weekly basis – with this add-on, reminding them to do that is easy.
For more information, I recommend that you look through the full documentation to ensure that this add-on will meet your requirements, prior to purchasing.