For merchants selling electronic files, the risk on ecommerce is low and the benefits are high. There are various methods available for ensuring that only paying customers receive files. These include dynamic management of FTP and HTTP download sites, direct transmission of files using HTTP and e-mail, and distribution of unlock codes which are applied to publicly available files.
The situation is slightly more complicated for businesses selling hard goods. Credit cards may not be charged more than 24 hours in advance of shipment. The shipping warehouse may need to sign off on shipment before the card can actually be charged. The ecommerce application would transmit the order to the shipping center, accept data about the shipment status, and then complete the transaction. Details would of course vary depending on the existing information systems in use by the companies involved.
An upcoming trend is toward software rental instead of outright licensing. Applications for tax filing to astrology chart generation are being web-enabled and charged for over the web.