There is a known problem with Builder Xcessory evaluations on SGI/IRIX that is fixed in the next release. If you are using IRIX, you should create a license file that contains the license key and then set the environment variable LM_LICENSE_FILE to point to it. Let's assume that you've put your evaluation license for BX in the file /some_path/mylicensefile.dat. Then depending on which UNIX shell family you are using, you would do one of the following:

For csh (and its variants):
% setenv LM_LICENSE_FILE /some_path/mylicensefile.dat

For sh (and its variants)
% export LM_LICENSE_FILE=/some_path/mylicensefile.dat