TMM does not use auto-renewal. You must manually re-purchase a license every 12 months to maintain PRO access.
Upgrading to the PRO version unlocks specific advanced tools not available in the free version: tinymediamanager pro license key updated
: If the license isn't sticking, use the Tools > Open data folder action to ensure the license.xml file is present and not set to "read-only." TMM does not use auto-renewal