The periodic points hook awards points to a user each time they visit your site at least once in a certain period of time.
For this hook there are two options to configure. First, the number of points to award. Second, the time period. The time period you select is the minimum frequency at which points will be awarded. For example, if you select to award points daily, a user will be awarded the points if they visit your site at least once in a 24-hour period. If they visit your site multiple times within 24 hours, they will only be awarded points once. If they visit again after 24 hours have elapsed, they will again be awarded points.
The plugin can only detect the identity of a user if they are logged in, so the user will only be awarded points for a visit if they are logged into your site.