Click the Check for Updates... command under the Help menu, and wait a little bit. (It usually takes a few seconds to check for an update, depending on your Internet connection speed.)

If an update is available, the latest change log will be shown. If you want to update your copy of DBF Commander Professional, click the Update button.

After the download of the update is complete, the current instance of DBF Commander Professional will be closed. Please make sure that there are no other running instances of the program. The downloaded installer will be launched. Install the update into the same folder where you have previously installed DBF Commander Professional. The default path will be shown on the installer's Select Destination Location page.

If you have installed the DBF Commander freeware version (up to 1.1.25), uninstall it before installing DBF Commander Professional.
Please do not use DBF Commander and DBF Commander Professional together at the same workstation, otherwise some commands may not work properly.