Heat turns THC-COOH (tetrahydrocannabinolic acid) which is the precursor to THC that the cannabis plant makes into straight up THC - this is what happens when you smoke weed or boil/bake it, and why if you cure your bud it gets more potent.
It also helps THC dissolve out of the plant and into the butter or oil.
Personally I would save the hash to be smoked
(wow, ninja'd, and yeah 11-OH-THC is made by your metabolism and turned itno yet another compound, confusingly also called THC-COOH sometimes, but it cannot become active again as the carboxylic acid is actually part of the formerly-THC instead of being in the form of CO2 attached to THC.)