Install the program.

Put the "lservrc" file into <installed dir>\bin and overwrite:
Windows: C:\Program Files\IBM\SPSS\Modeler\18.0\bin
MacOSX: /Applications/IBM/SPSS/Modeler/18/SPSSModeler.app/Contents/bin

Or use the following license code using the License Authorization Wizard:
4PTTHADF8ZQE5ZCZB4CP9F6OQ5JSBBO8WWW26797OLXJ6SJSSQ6AH2KAI8H3RKDZ83UNFCIGOVZG7LZIQ7BGPY48SRE6

NOTE: 
Under MacOSX, using the License Authorization Wizard may give an invalid license error.
It even does that with the default trial code! So use the lservrc license file instead.