You simply buy the software online (often for less money than a physical edition costs), activate it immediately after purchase, download and install, and voila. There’s never a question of whether or not the software you want is available, digital software is always in stock, or available in whatever quantities the end user needs.
Once it’s downloaded and installed, the product key for that software is associated with their account.
The convenience of buying digital also means end users can buy their software at any time of the day or night.
Making software available to your customers via ESD is a smart move. Not only will it benefit your business, but your customers will appreciate the ease and convenience you offer them motivating them to come back to you time and time again for their IT needs.