You should check this thread: Upgrade community to DE and this one: Can we direclty upgrade the Sonarqube community edition instance to Developer instance after purchasing Licensedirectly or have to do uninstall the existing one install the new one? - #3 by Ashu6753
Especially this part:
Download the Developer Edition here Download | SonarQube
Then use the same Database you used with the Community Edtion in …/conf/sonarqube.properties and use the license in../admin/extension/license/app
Then, if the ServerID is OK, you would be able to put your Developer license key in your SQ. If the ServerID changed, just contact us (Sales Rep) to have your new updated key.
Carine