Ah… yeah the Xilinx tools only support the LX150 with a non-webpack (i.e. real) license. Do you just need programming? It’s possible Impact supports it, but you won’t be able to generate the bitstream.
If you’ve just got a few things to do, you could always get a trial license for something like ISE Design Suite: Logic Edition, and generate your bitstream. I assume they still have 30-day license available.