Open JPLAY app on your iPhone / iPad. Go to 'Settings' screen. Then scroll down go to 'Database' and tap 'Backup database'. The backup file will be created in the 'Files' app.
You can copy the file to a different location by sharing feature as shown in the video here or connect your iPhone / iPhone via cable to a computer and copy the file manually. Keep in mind that without creating a back up, your database will be removed when JPLAY iOS is unistalled or if you want to install it on a different iOS device!