The biggest benefit in the license change is that there is no longer a delay to the updates for the free Home User feed. As soon as the plug-ins are available, they will be current. However, companies that used Nessus' Registered Feed will now have to pay for the privilege by subscribing to the Professional Feed, which gets you access to plug-ins that are aimed at enterprise use such as host configuration checks that conform to the Federal Desktop Core Configuration requirements and the Center for Internet Security checklists. In addition, the Professional Feed provides the ability to search content for sensitive data.
Many commercial vulnerability scanner companies typically require companies to register network addresses or DNS names as part of the licensing process. One reason is because the products are priced on a per seat basis. The other reason is to keep administrators from using the scanning product on unauthorized computers.
The Home Feed version of Nessus has no restrictions on its use. The license is based on the honor system. Ron Gula, CEO of Tenable, stated in an interview that the decision not to enforce home use from within the product is because, in his experience, the honor system works. Using the Home Feed in a company is a violation of the license and companies are willing to risk violating the license. In addition, placing onerous restrictions on software licenses becomes a support headache that affects legitimate users.
Gula also said they learned a lesson with Newt, an early version of Nessus for Windows. Newt was restricted at a single subnet and Tenable received a lot of negative feedback on the restriction. Rather than alienate users, the restriction was removed.