Student license for FFT IP Core

Hi, thanks for the answer. Unfortunately I still have an error "Error (204009): Can't generate netlist output files because the license for encrypted file "C:/Users/Mariusz/Desktop/praca magisterska/kody/vhdl/fft prime/fft/synthesis/submodules/auk_dspip_r22sdf_stg_pipe.vhd" is not available"

I think I did everything as you told me. First I deleted db and incremental_db folders from my directory, then I removed all the FFT files from the project and generated it all from the beginning. Then I added the newly generated files for the IP to the project and try to compile it. I'm not sure what is still the problem