This is because it is a paid search engine with a free limited trial. This trial is limited because the search inquiry is costing them money and they don't have

This is because it is a paid search engine with a free limited trial. This trial is limited because the search inquiry is costing them money and they don't have VC money to through on growth. Neither they plan to follow this growth path. They focus on quality for the targeted market. And to be honest, they succeed in that until now.