Green’s Dictionary of Slang

(US) comfortably, easily.

1835

W. Otter Hist. of My Own Times (1995) 86: I quit my trade, and began to keep her bar for that winter. I lived jam . . . til some time in the month of March. [Ibid.] 119: The dollar and a quarter was all spent in wine, brandy and cakes, while that lasted we lived jam, and never gave up until the money was all spent.