The Amita Drive itself is an extension of the regular Compac Drive, which is found in most all mechanical devices. Once connected to the Compac drive it cannot be removed. The drive allows the Nirvash typeZERO to start the "Satori program", which allows the Seven Swell Phenomenon, an immense force that can create a lot of damage.
During the course of the series, it is learned that the Amita Drive responds to the feelings of Renton and Eureka. The first time is when it causes the Nirvash typeZero to act on itself and save Renton and Eureka after their encounter with Anemone and Nirvash typeTheEND with the Coralians. The Nirvash typeZero moved on its own again when Holland and Charles Beams were fighting in the hangar. This is believed to be caused by Renton being close to being shot by Ray Beams when Talho tackles her.
At the end of the series, the Nirvash typeZero reveals its sentience and speaks to Renton and Eureka after they become one. It explains how with the emotions of love, devotion, and other surrounding their relationship that she will finally be able to achieve enlightenment. Given "Satori" means Enlightment is Japanese, the initial "Satori program" had this goal in mind. It is also likely that the Amita Drive, by allowing the Nirvash typeZero to interface with human-type emotions, allows it to understand and process deep love, completing the program.
Eureka Seven: AOEdit
In Eureka Seven: AO, the Amita Drive makes an appearance on the Nirvash TypeZERO Spec 2. Eureka brought it into Ao's world after being trapped inside of a Scub Coral while, ironically, performing a test with the Gekko on why the Scub Coral were disappearing from their world. It remains attached to the Compac Drive after Naru Arata and Truth take control of it. It is not used to make a Seven Swell during it's course in Eureka Seven: AO.