Neville was in the DA, and was required to grow up considerably, during the war. His friends helped him to realize his strengths and expand upon them, leading to his joining the volunteer healers during the war and, despite his lack of experience, gaining useful knowledge and contacts in the area.
He was forced to fight a couple of times, and while Harry's training and a good deal of luck kept him unharmed, he admits that he wasn't built for that life. His new friends in the healing field helped him to pass NEWT Potions (just) and he was accepted into the St. Angia's Training Centre for Healing and Practical Medicine, where he now studies full-time in order to work in Destructive Medicine (which doesn't mean medicine that's destructive… it just works to treat the destruction of the mind and body).
He lives in a flat that he pays for, along with his tuition, with his inheritance and the odd assistanceship now and then. He keeps up with his Herbology, of course, but although it comes in handy sometimes at the Academy (especially during, you guessed it, Potions..) it's mostly a hobby.
Neville still has ties with his year-mates from Hogwarts, of course, as well as his friends from Gryffindor and the DA. He may also make reference to his current schoolmates from the Academy.
Neville's Gran, Augusta Longbottom, fell into decline recently and died peacefully in her sleep. His parents remain in St. Mungos, though he visits them regularly and secretly harbors hopes of one day discovering a cure to their affliction. (Good luck, Nev.)