Similarity is programmed and supported by GAR, a Russian company so that inquiries made in the U.S. may take a while to get a response. The website offers a 64 bit version, which is the one I downloaded, but appears not to make full use of 64 bit addressing in its use of memory, at least, not in a way that would improve performance. In fact, while they claim the paid version is faster, I am running it against a drive with just over 58000 music files and while the FREE version could do this in four hours, the PAID version has been running for 15 hours, already and, though 70% done, tells me it need another 15 hours to complete. Audio Comparer might have been a better choice.
