The standard procedure to transfer database uses backup files.
in Demo version
Step 1) Run Demo version.
Step 2) Go to Demo's main screen > MENU > Settings > Backup & Restore > "Backup & Restore.. Local"
Step 3) Create a backup using "Create Backup" button
This will create backup file in "/ClassBuddy/backup" folder.
Step 4) Now, close the Demo version and go to Pro version.
in Pro version
Step 6) Go to Pro's main screen > MENU > Settings > "Data transfer.. Demo > Pro"
There you will see all the backups you created in your Demo version.
Step 7) Select the latest backup and restore it.
Step 8) Restart Pro version and check if all the data are transferred.
Step 9) Once the transfer is completed, you don't need Demo version anymore. Go to Android market and uninstall..