Not Enough Core Licenses to Continue

[HayleyCleveland]

I am trying to purchase 3D Analyst. I currently have ArcGIS Pro Basic and ArcGIS Desktop, licensed to one user (myself) within my organization. When I add it to my cart, this error pops up and won't let me check out. I use ArcGIS Pro and Desktop both, so I don't know why it thinks I don't have a license to use this. Any ideas? 

[JayantaPoddar]

It would be wise to connect with your local Esri Distributor or Esri for more clarification and software purchase.

I am not suggesting anything else, for now.

[IaraNascimento]

It could be that the licenses are concurrent and are already in use or you need to purchase the extensions. Check with your organization and Esri.