The spell Protection from Evil and Good reads:
Casting Time: 1 action
Range: Touch
Duration: Concentration up to 10 minutes
Do you only need to touch your target during the casting time or do you have to maintain physical contact to concentrate on the spell?
Best Answer
From "Range"
Thus no, you don't have to maintain contact (unless the spell says so) when casting a touch concentration spell, just like you don't have to remain in range to concentrate on other spells, as the range is only a limitation when the spell is cast, not when sustaining it.