As explained in License Compliance Components, the number of purchased licenses is one of the three primary pieces of information that is required to determine the product’s license compliance. You license data can come from two different sources:
Catalog Products and Purchase Records: A catalog product identifies a software product for which you have purchased licenses. When added to an entitlement, a catalog product’s licenses become available for consumption by the entitlement’s installations.
A catalog product’s licenses come from purchase records for the software product. If multiple purchase records include license purchases for the software product, all licenses are rolled up to the catalog product.
Using catalog products and purchase records as the data source for your purchased licenses is the recommended method. Each time you add a purchase record for the software product, the catalog product’s available license quantity is automatically increased by the number of new licenses.
Purchase Summary Records: A purchase summary record lets you directly enter a license quantity on an entitlement. The summary record includes the product’s description, cost, and license quantity. The disadvantage to using a purchase record summary is that it doesn’t enable you to track the product licenses through a catalog product and a purchase record.
An entitlement can use one or both sources for its available licenses.