The Amontec JTAGkey is a USB to JTAG adaptor sold by the Swiss company, Amontec. Amontec also offer a very inexpensive variant called JTAGkey Tiny, which is more or less the same hardware, but without level shifters. This means that low-voltage signals might not be picked up.
However, on the Neo1973 Hardware, the JTAG voltage is 3.3Volts, so no level shifter is required, and the JTAGkey Tiny can be used.
Please note that encourage using the new official Debug Board over other JTAG boards.