What is the beacon DFU How can I use it?

[GunMin]

First, I flash the softdevice, then I flash the bootloader, then I use a smartphone app to upload an application to the device via BLE.

but, The first operation only. When I try to re-download, Is not a search.

How do I use it?

and if I sell it by creating a product, creating Does any way?

Did I put a hex file for the application in any way with the product? (How to load the application when I create a product)

[shibshab]

I am not sure I understand your question, but I will give it a go.

The bootloader is capable of flashing hex files to your device in the same way as conventional wired options (J-LINK over USB etc.)

The typical use case would be that the device comes shipped with all three hex files in place (bootloader, softdevice, application), and that when an update to one of these hex files is required you would use the bootloader to perform this update.

This way you can flash your device without having to connect a wire to it.