ftp://surfer.nmr.mgh.harvard.edu/pub/docs/license.freesurfer
http://surfer.nmr.mgh.harvard.edu/registration.html

If the file is in the right place and has the right name (freesurfer/.license), make sure that the environment variable MRI_DIR is set to your freesurfer directory, i.e. the same as your FREESURFER_HOME directory. This is set automatically by sourcing the FreeSurferEnv.csh file, as described in the installation instructions, so sourcing your usual set up script file should work.
2003-Jul-30 10:35am kteich