NServiceBus.Persistence.NonDurable adds support for NServiceBus to persist in-memory, in a non-durable fashion. Any data is lost when the process ends, making this persistence option suitable for a very small range of scenario's in which the system can afford to lose data.
It is part of the Particular Service Platform, which includes NServiceBus and tools to build, monitor, and debug distributed systems.
See the Non-durable persistence documentation for more details on how to use it.