Fly-by-Wife I can assure you that having worked on numerous large IT projects during my career I do understand the concept of what a volume licence is. It does not refer, as you seem to suggest, to some sort of discount for buying a large number of individual licences, it refers to buying a single licence that authorises the holder to install and use the software on multiple devices. It is important to understand that there is a difference between a product key and a licence, they are not the same thing. When someone buys a software licence they are entering into a legal contract with the software provider and the licence sets out the terms and conditions under which they are authorised to use that software. In the case of a retail product that might be a licence that allows you to install the software on a single computer and you would be provided with a single product key that enables you to do that. In the case of a volume licence that might be a licence that allows you to install and use the software on up to 100 devices and you might be provided with 100 product keys to enable you to do that.
The product key on it's own is not a licence to use the software and if you read the section of the document quoted in my previous post it clearly says that dividing up a volume licence and selling only part of it is not allowed.