WorpDrive unlimited means that we don't, under normal circumstances, monitor the usage of your storage. We don't, normally, charge for excessive disk space usage.
This, however, is open for abuse unintentional or otherwise and so it is subject to a Fair Use Policy.
We reserve the right to restrict, inhibit, or remove sites that consistently break the Fair Use Policy. To understand more about this, see here.
Not all WorpDrive subscriptions are "unlimited". Older subscription are typically metered and come with overage charges. We didn't really like this approach, and we learned that our clients didn't either. This is why we introduced "Unlimited" backup storage.
For more information on unlimited WorpDrive backup storage, read the blog article here.