The Trial version is limited to 4 pinned domains, 4 matching rules for advanced debugging tools (Map Local, Map Remote, Breakpoint, Allow/Block List and Scripting), and no new tabs.
The Premium version comes with a year’s worth of updates, multiple tabs, unlimited pinned domains and unlimited rules for advanced tools.
If you're the owner of the Proxyman license, you can manage your devices, which are associated with the License by adding, removing. Please open License Manager
After purchasing the Proxyman License, you can active it by opening the Proxyman Menu -> License...