When working with the API, it is important to understand the conceptual relationships of customers, users, SKUs, and licenses.
An existing G Suite customer can create users in the administrator control panel. By default, these users are auto-assigned a license to use G Suite.
After purchasing G Suite, the customer can also buy other licenses, for example Google Drive storage licenses. Google Drive storage has 8 tiers of available storage licenses, ranging from 20 GB to 16 TB. The customer must first activate a Google Drive storage subscription, and then can assign storage licenses for any of these tiers using the License Manager user interface. The customer can also buy Google Maps Coordinate independent of G Suite, and then assign Google Maps Coordinate licenses using the same user interface.
These licensable entities—Google Maps Coordinate, Google Drive storage 20 GB, Google Drive storage 50 GB...Google Drive storage 16 TB—are called SKUs. This API allows a domain administrator to programmatically assign licenses of SKUs to a particular user and can be used along with the License Manager user interface. You can also unassign, and re-assign licenses for a particular user, much like in the user interface. The API allows the same programmatic license assignment for G Suite reseller administrators and their customers.
For users on a flexible plan for any of these products, assigning, un-assigning and re-assigning licenses using this API will have monetary impact, and will result in charges to your customer billing account. For instance, if you are on a flexible plan for Google Drive storage, assigning a user a 20GB license will result in charges being posted to your account, prorated from the time the assignment is done. If you are on an annual plan, you would already have committed to paying for a certain number of licenses upfront, and you can only assign as many licenses to individual users as your commitment.