Flex tokens are a virtual currency that you buy from Autodesk. They are used both for cloud services and pay-as-you-go product access.
All products and services purchased on the same contract pool their cloud credits together. You can purchase more credits independently, although you must be careful to purchase them on the relevant contract. Some contracts allow an unlimited number of users access to cloud services. For general information about Autodesk Flex tokens see the Autodesk Flex Frequently asked questions (FAQs).