VilaNet(VilaX) service data resets once a month, on the same day of the month as your service's billing due date — for example, a service with a due date on the 25th resets on the 25th of each month. This is a calendar month (about 28 to 31 days depending on the month), not a fixed 31-day interval, and it is not tied to your original purchase date.
*The billing due date is not the same as the renewal date, and renewing does not reset your data.
OpenConnect (AnyConnect) resets on the 1st of each month.