1998 Acura EL Battery keeps dying

My battery has kept dying over the last few months, even when it was warmer. I can easily jump start the engine using my mobile starter, and it usually can last a couple of days, depending how much driving I do before I stop. Therefore it seems to me that the battery does recharge to some point, however it "leaks" pretty quickly overtime.

Before I go and buy a new battery, I was wondering if anyone had an idea if what the actual problem is. Does it sound like the battery needs changing, or could something else cause the battery to leak energy?

Thank you,
Best regards.