LISP was the fourth in the line. Three sample units (Alpha, Beta, Gamma) before it were trying to do the job they were programmed to: to make their owners rich by not using proprietary chassises like Cybot Galactica. They wanted their own. They tried chassises more specialised...but they cost a lot of money to develop.

Mk4 was different. An ancient B1 chassis refurbished. The fulfillment of its life would be self-sufficiency and weapons use. And boy was it good at that. The owners of the design were happy, as it was bringing in the desired results. The slight issue with its communication unit? Well, it might as well be the MK4's sex appeal.

When Ras Q'uandel died on Belsavis and the news reached his family, of course, they were devastated, and realized that they would need to help their daughter. Hence, they spent a considerable amount of money to send LISP over to Mylla. The only request was that they don't need only 50% of all the money the droid makes. The rest it can keep, to collect money to buy its freedom.

All was going well until a series of catastrophic events cascaded on the poor droid's head.

Some of its constructions caused a ruckus in Cantrell, some people cried wolf, they weren't happy with the quality. Whether they were right or wrong, we'll never know. What we do know is that the droid picked up some bad reputation along the way, and that meant LISP4 felt it had to go.
The second problem was that LISP4 was abducted from the workshop it occupied, and done so by a Hutt. Said Hutt had the help of a droid and as a result of a series of memory wipes and reprogramming attempts, L1SP4 would build up a strange....affection towards the worms. Funnily enough, the Hutt the droid owes credits now knows this, and the Force knows why, but doesn't abuse this opportunity.
Three, the partial droidic brain catastrophes. The reprogramming attempts that were fighting the built-in restraints inside the droid's brain underestimated the strength of the hard-coded connection to the Q'uandel family and were crude enough to harm the droid's internal systems, resulting in a partial memory wipe. Whatever skills LISP4 possessed before is now gone. There are some basic, we could say, muscle memory abilities remaining, and some of its communication modules are working at a better efficiency. The droid, thanks to the tinkering with its inside, is reborn.

As for why its outside layer looks the way it does: LISP4 has been abducted once, it doesn't want the unfortunate event to happen again.

Progress. LISP wants to be independent and survive as long as possible.

Servitude: 20 - LISP4 is owned by the Q'uandel family. It is aware of this fact but feels more...reluctant to comply with what comes with this obligation. The reason for that decrease is the fact that it has grown to be completely self-sufficient - what's more, it has picked up a job at the SIS. However, it knows what it owes to its makers, and it shall repay the debt.

LISP4 used to look like a classic B1 droid, but its outside went through significant changes, and now looks as if it were designed to deflect explosions, acid splashes and fire.

It also has a lisp.