Basic Cloud/SaaS: If you are a small SaaS company and/or are targeting the cloud and wish your message processing to be throttled to keep costs low, the Basic License is for you. Limited to a single site or datacenter and throughputs from 2 to 32 messages/s, this license keeps costs low as you scale. There is also the option of a monthly Subscription License for higher performance with a flexible pay-as-you-go per-core licensing model.
Corporate and SaaS: If you are a larger SaaS company or building high-performance system inside the corporate firewall, the Standard License is your best choice, removing any performance-inhibiting limitations. Licensed per server core or virtual core, whichever is lower.
Enterprise and Global ISV/SaaS: If you install your software on many machines and/or across many sites, the Royalty-free License is most appropriate. Licensed per-developer programming against the NServiceBus API (including the system's messages), this license covers all machines and sites the software is deployed to and also has all performance-inhibiting limitations lifted.
Fortune 500: If you have many developers building a system, like with off-shore teams, or will be using NServiceBus across many systems in a single line of business or across multiple lines of business, please Contact Us to discuss your specific environment and needs.
Open source projects who wish to build on top of NServiceBus can do so for free using the Reciprocal Public License 1.5.