The Spotfire licenses "Use Custom Made Tools" and "Spotfire Extensions" both sound like they are meant to provide users access to Spotfire custom extensions developed using the Spotfire SDK. There is a difference between these two.

This article explains the difference between the TIBCO Spotfire licenses "Use Custom Made Tools" and "Spotfire Extensions"

Use Custom Made Tools
The "Open Custom Made File" is related to the license "Use Custom Made Tools". The "Open Custom Made File" license will enable/disable custom extensions (custom file formats) entries in the File > Open From menu. In practice, it is possible to create custom import tools that allow Spotfire to open virtually any file format (e.g., SPSS files). The "Use Custom Made Tools" license is related to enabling/disabling any Tools created related to these custom files, e.g. Insert rows.

Spotfire Extensions
This license enables users to view and use custom extensions which may be added to Spotfire. When new custom license features are deployed on the Spotfire Server, they will appear under this license. These can then be enabled or disabled for each individual license feature.

Doc: Spotfire Analyst license

• https://docs.tibco.com/pub/spotfire_server/10.3.9/doc/html/TIB_sfire_server_tsas_admin_help/GUID-DF469AD9-F4C2-4701-A241-9292AC0E7AC2.html