This package consists of two dlls:

Themis.dll
Themis.NHibernate.dll

The first is the basic version ot Themis, which covers all authorization tasks with no integration with NHibernate.
The second is an ILMerged version of Themis and original Themis.NHibernate and provides standard Themis behaviour with additional support for NHibernate. To use Themis choose one dll matching your needs and reference it in your project.

For more information visit the official page:
http://themis.codeplex.com/

Happy Themising!