Trucy uses the coin to help out Uncle Larry.

In the hands of many other people, a magical item like the gold coin would have been used for personal gain, or to smite those who had wronged the holder. Trucy Wright was not that kind of person. No, with the phenomenal arcane power she now held, all Trucy Wright could think about was how to help people she knew and cared about. And no one needed more help than Uncle Larry. One of Trucy's many honorary uncles and aunts, Larry Butz had struggled his entire adult life, and Trucy knew all about it.

Such knowledge did not come through difficult investigation, but from the fact that Larry would tell anyone and everyone about the troubles he faced given their time and attention, and even their attention wasn't really necessary when you got right down to it. The biggest sources of strife for the man approaching his forties were twofold: he had issues holding down a job, and he had issues going after women who would inevitably leave him. If Trucy was going to make his life better, she was going to need to solve one or both of those issues. But how?