The standard procedure to transfer Barcode Express database uses backup and restore.
For this,
Step 1) Run Barcode Express Demo version.
Step 2) Go to MENU > Settings > Backup & Restore > Backup & Restore
Step 3) Create a backup using "Create Backup" button
This will create backup file in /BarcodeExpDemo/backup folder.
Step 4) Now, close Barcode Express Demo version and go to Pro version.
Step 6) Go to Pro version's main screen > MENU > Settings > Data transfer
There you will see all the backups you created in your Demo version.
Step 7) Select the backup you just created and restore it.