A license has to be purchased, and I think only Steinberg's Cubase and Apple's Logic Pro offer it as a feature. Since Steinberg is owned by Yamaha I suppose they might be allowed to use it in a hardware synthesizer, but as far as I know they do not.

Edit: this table says that Access have hardware synths with Hermode tuning: http://www.microtonal-synthesis.com/micro_af.html . Elsewhere I see Waldorf listed as having offered Hermode in some models.