It is not often that early SpaceX memorial medallion’s come up for purchase. In this case it was to commemorate and mark the first flight where a privately developed spacecraft attached to the ISS, the beginning of the commercial space industry. This medallion is in the original packaging with Certificate of Authenticity from SpaceX (see more in photos). This medallion commemorated the COTS-2 mission which you can read more about here: 

https://en.m.wikipedia.org/wiki/SpaceX_COTS_Demo_Flight_2

“This limited edition coin commemorates the Commercial Orbital Transportation Services (COTS) mission (C2+), May 22-31, 2012, when SpaceX’s Dragon became the first privately developed spacecraft to attach to the International Space Station.