CARA is freeware, i.e. it can be used for free by anyone. The users are obligated to mention the use of CARA in their resulting publications*.
The software and documentation are provided as is, without warranty of any kind, expressed or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

*
Please reference the book The Computer Aided Resonance Assignment Tutorial by Rochus Keller, first edition 2004, ISBN 3-85600-112-3, CANTINA Verlag. Alternatively you can cite Rochus' PhD thesis, Diss. ETH Nr. 15947. It would also be helpful if you could mention in your publication that CARA can be downloaded for free from www.nmr.ch.