We licence Premium Data on a per instance basis. Each instance is a single physical copy of the Premium Data. This means you need to buy sufficient instance subscriptions to cover all the physical copies of the Premium Data you will use.
For example - 2 physical machines, one for production and one for staging (pre-production testing) each running 2 virtual servers with each virtual server containing a copy of the Premium Data would require the purchase of 4 instance subscriptions.
Please contact us if you require an Enterprise licence for unlimited internal usage or have alternative volume licencing requirements.