Hello,
Before any update - please do full site backup(database and files)
after that please in free version select option "update"
Uninstall free version real estate manager soft.
Install pro version real estate manager soft.
recover folders:
{site}/components/com_vehiclemanager/edocs
{site}/components/com_vehiclemanager/photos
best if any test you first will do on test environments
Thanks,
OrdaSoft team