Kenn is a quarian merchant that runs Kenn's Salvage on Omega station. He arrived there while on his Pilgrimage, but was trapped when all his money was stolen and he could no longer afford to leave. Another merchant, Harrot, is preventing him from earning enough money with his salvage operation to leave the station by forcing him to sell his goods at higher prices, costing Kenn business.
Shepard can persuade Kenn to lower his prices or offer to convince Harrot to release the quarian merchant from the agreement, thus allowing him to set his own prices. In addition, Shepard can also offer to pay for Kenn's ticket outright (or after leaning on Harrot), after which Kenn will no longer be at his store. If Shepard convinces Harrot to force Kenn out of business, then he will no longer be at the store and the discount will no longer be valid.