which versions are you using : Version 8.9.1.44547
what are you trying to achieve : Recently we have purchased developer soanrqube license but we couldn’t able to see any option to apply the license on sonarqube UI.
what have you tried so far to achieve this : not see any relevant information yet on sonar doc.
you only see this field when you deploy a comercial edition of SQ. so when you just boughed the developer license you need to setup a developer edition of SQ and apply the license there. all your data is persisted in the database, so the high level workflow could look like this:
shutdown community edition
setup and configure developer edition (i think you can just use your old sonar.properties file)