If you decide to purchase spock, follow the instructions in the file license.txt of the spock distribution, or see http://quorum.tamu.edu/jon/spock/license.txt. We'll generate and send you a permanent LICENSE to replace the trial one. For those academic labs without current grant support, or for those for whom purchasing spock would present a financial hardship, we offer discretionary gratis licenses as discribed in the license.txt file.
Note that in some cases, there's an environment variable that must be set for spock's licensing routines to work. If the unix hostname(1) command on your machine does not return a fully qualified host name (i.e. it doesn't have the domain) set the variable $SP_DOMAIN to the local domain. This command should be put in the system Spockrc file as described below.