There is a free 64-bit version available with limits that don't seem harsh at all:

The 64-bit kdb+ On-Demand Personal Edition is free for personal, non-commercial use. Currently it may be used on up to 2 computers, and up to a maximum of 16 cores per computer, but is not licensed for use on any cloud – only personal computers. It requires an always-on internet connection to operate, and a license key file, obtainable from ondemand.kx.com