Licenses

If you purchase your licenses directly from Microsoft, your Licenses page will show your products, the number of valid licenses you have for each product, the number of expired licenses (this includes disabled licenses, but not necessarily deprovisioned ones), and the number of licenses assigned, with a prompt to assign licenses if you have unassigned ones, or unassign licenses if you don't have enough. There will also be a link for each product, to allow you to buy more:

Licenses page

If you purchase through a CSP partner or another distribution program, you won't see the prompts to assign, unassign, or buy now. Your distributor or Microsoft partner handles that; you should contact them for more licenses. Instead, you may see a link directing you to contact information for your Microsoft partner.