You should only move to the new license model when your commercial agreement is updated to use the new product licenses (Spotfire Enterprise, Data Science, Analytics, Analysis Consumer, Analysis Viewer). In this situation it is required to use the new license model. See Upgrading to 14.0.8 and 14.5.0: New license management for details.

Upgrade, with legacy license model:
If you have an existing commercial agreement that references the legacy product licenses (Spotfire Server, Automation Services, Statistics Services, Analyst, Business Author, Consumer), you should just upgrade to 14.0.8 or 14.5 and maintain the legacy license model (this is the default setting for upgrades). Later, when your commercial agreement is updated to use the new product licenses you can follow "Migrating licenses after upgrading" section to move to the new license model.

New Install, with legacy license model:
If you have an existing commercial agreement that references the legacy product licenses, and you are doing a new install of 14.0.8 or 14.5 or higher it is important to note that the default for a new installation is to use the new license model. That means that after installation you will have to modify the licenses.version server configuration property from the default value to 1, per "Changing the product license version".

Changing the product license version:
When it is time to move to the new product license model, there are some important considerations:

• Ensure you have a database backup before making changes.
• Before upgrading, use the show-named-user-licenses command (see Manage license features and named-user licenses for more details) to validate the current license configuration. This can help highlight any license misconfigurations (such as using Analyst features for user groups that are supposed to be Consumers, etc.) that are best resolved before moving to the new license model since this will make the automatic migration less accurate. 
• Thoroughly test the license migration process, especially if you have complex group structures, custom licenses, or have made major modifications to the groups and license assignments

For any compliance or commercial license questions, please discuss with your Spotfire account team. For any technical questions or issues with the license assignment or migration process, please contact Spotfire Support.