A usage period is a monthly period that starts on the day when you create an account and resets on the same day each subsequent month. For example, if you create an account on the 10th of January, your first usage period runs from the 10th of January to the 9th of February, and the second usage period runs from the 10th of February to the 9th of March, and so on.

If you upgrade your account to a paid plan, the day of the month that your account renews becomes the day that your usage period...