Yes, APPANAGE is a Scrabble word!

Letter values in Scrabble US: A 1, P 3, P 3, A 1, N 1, A 1, G 2, E 1.

Is it a valid word?

APPANAGE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

any customary and rightful perquisite appropriate to your station in life
a grant (by a sovereign or a legislative body) of resources to maintain a dependent member of a ruling family