Charles Ellicott Commentary Deuteronomy 12:15

"Notwithstanding, thou mayest kill and eat flesh within all thy gates, after all the desire of thy soul, according to the blessing of Jehovah thy God which he hath given thee: the unclean and the clean may eat thereof, as of the gazelle, and as of the hart." — Deuteronomy 12:15 (ASV)

Notwithstanding you may kill and eat flesh. —This may very possibly be intended as a slight modification of a law made for the wilderness journey (Leviticus 17:3–4). There the “killing” of an ox, or lamb, or goat is forbidden anywhere except at the door of the tabernacle. The word “kill,” though often used sacrificially, cannot be limited to sacrifice in that place, although the animals mentioned are all sacrificial animals. It would seem that the practice of sacrificing those animals elsewhere, very possibly for the sake of the feast which followed, had become so common that it was necessary to forbid the killing of them anywhere but at the door of the tabernacle.

But the continuance of this precept in Canaan would stop the eating of flesh altogether. Hence the exception made here.

As of the roebuck, and as of the hart. —The frequent mention of these animals in this connection suggests the idea that the hunting and catching of them may not have been an uncommon thing in the wilderness.