Upgrade Path to Version 9Browser Info Environment
Formdiable for V9 is new version for Formidable Full. You need to purchase the new version for using Formidable in V9.
Always create a backup first!
The best way is to unistall Formdiable Full without removing the data. Then upgrade your Concrete5 installation. Purchase Formidable (v9) and install.
Before installing the addon will notice the old Formidable Full data and allows you to import old data.
That should do the trick!