In Evolution: The World of Sacred Device the Launcher family debt starts at 80,000. If Mag pays it off before the showdown on the Imperial Cruiser, he will be rewarded with an Attack+70 booster for Cyframe users.
After clearing the story, a new quest is added and Mag has to pay down a new debt of a staggering 200,000 accumulated for repairs to the Sea Otter by the Society after the battle with the Empire. Once this is paid off, Mag will be rewarded with an accessory that can only be equipped by Linear, though at that point in the game there is not much use for it as there is nothing left to do.
Once a dungeon is cleared, if the debt has not been paid off then a certain amount of the relic money will automatically go towards paying off the debt. This provides an incentive for the player to pay it off.
The debt can go up if Mag and his party die in the ruins and have to be rescued by the Society. This will result in a fine of 1000 being added. If the player is not careful, Mag can go back into debt this way.