Recurring true-up period as license attribute

We generally conduct true-ups at renewal every 12 months, but we do these more frequently for larger customers. For large enterprise customers, we sometimes do true-ups every 3 months and 6 months, when we review the users over license and charge the customer for the difference.

We should be able to set a true-up period as an license attribute. This should be in months and default to 12 months. This attribute should influence the Maximum Users that we show in the License panel of the admin area (it should reflect a rolling X months, as defined by this attribute).