By license I'm guessing you mean Quartus license, not Nios II? The Nios II CPU requires a separate license. If you don't have it you have several options:
1) use the smallest Nios II/e core with Quartus >= 9.1. This variant of the CPU is slower but doesn't require any license
2) use the Nios CPU in Opencore evaluation mode. In that case you'll need to keep the board connected through JTAG when you run the design, and you won't be able to do any simulation in Modelsim. AFAIK the error you are getting is when Quartus writes a netlist for the simulation for Modelsim, and it fails because of the lack of license. You must disable the simulation in your Quartus project in order to compile it.
