4 answers

Hi Valerian,I think there is no option to change the edition of our SF account.⌗But contact the salesforce support and confirm that. refer this link.
One solution is there, you can create new developer edition org. Move all the configuration records class pages from Professional edition org. Then you can start working from here.Note: You can use the same email address for any number of accounts. You can't use the same username. If you want to use the username you've set up in your trial, then change the trial username to something else (like your@emailaddress.com.trial.Then you can use the original username which you have used for your professional edition with the new Developer Edition.Hope this helps.Kindly mark this as solved if the reply was helpful so that it gets removed from the unanswered queue which results in helping others who are encountering a similar issue.Thanks,Nagendra