Shozam generally allows up to two concurrent activations at one time. This is done to allow users to have Shozam activated on a desktop and a laptop, as an example. However, usage is limited to one user. For specific language of licensing terms, please refer to the End User License Agreement (EULA), particularly section 5.2:

http://www.shozam.com/legal/license.htm 

Please also note that additional activations may automatically disable older activations.