Hello Dirk,
Thank you so much for doing business with us. As per your question, Free theme can not directly updated on the pro theme because, free theme has less options but pro has more. So, we are so sorry that you have to do some setting once again after activating pro theme. Because, the features and widgets on the pro theme are really greater than the free theme. So, you just need to manage the Appearance > Customize setting, no all the setting need to setup again. You just need drag and drop widget and some setting to save. If you have any confusion regarding this, let us know. We will mentor you in every steps.
Best Regards,
Acme Supports