Quandl is a startup that has taken outside investment. I am sure the shareholders would want the company to keep going. I imagine it is a highly profitable business. Here is the bitcoin data https://www.quandl.com/search?query=bitcoin I am sure there is a free database on quandl that has metal prices back more than a few years. Try the CME one for a start.
They have free data for precious metals for 40 years, but industrial metals only 5 years. Bitcoin is the only cryptocurrency they have data for. They offer free data as a teaser. Once the company is established they will phase it out. Providing services for retail investors is a loss leader; they would much prefer to offer highly priced data to institutional investors.