In Fusion, the Purchase Manager screen lets you purchase subscriptions, extensions, and Flex tokens in one place.

Example of the Advanced Capabilities tab in the Purchase Manager when you have a paid subscription.
What's available in the Purchase Manager depends on the Fusion product you have. Typically it’s organized into three tabs to match your needs:
When you add a Fusion subscription, extension, or Flex tokens to your cart, secure checkout continues on the Autodesk website.
You can open the Purchase Manager from the Application bar in Fusion, which varies depending on the Fusion product you have:
If you’re on a trial, click Subscribe Now to open the Plans and Pricing tab or Extensions
to open the Advanced Capabilities tab.

If you’re using Fusion for personal use, click Upgrade
(then select See plans and pricing in the flyout) or click Extensions
.

If you have a paid subscription, click Extensions
.

To view Flex tokens, open the Purchase Manager using one of the options above, then switch to the Flex Tokens tab.
Bring Your Own Subscription (BYOS) is a policy that defines access to Fusion, as well as some other Autodesk products.
Fusion administrators are responsible for setting up a hub for collaboration.
While Fusion contract managers can assign and manage individuals’ access to subscriptions, Fusion hub administrators have the ability to invite people to a hub without needing to assign a subscription.
If a person without an active Fusion subscription accepts an invitation to join a hub, they’ll start a free 30-day trial, (starting once they first access Fusion) unless previously used.
If a person is invited to a hub and already has a Fusion subscription, they can start using the hub:
For more information on BYOS and Fusion, see the Subscriptions & Other Offerings page.