purseverance
Refers to an unwillingness to give up on your efforts to mooch off of someone (in other words, to get him to "open his purse" for you).
Sometimes the term "purseverance" can have a somewhat opposite meaning, as well --- it can also refer to the ongoing efforts that an overly-trusting person who actually HAS "opened his purse" to a neighborhood moocher feels compelled to maintain in an attempt to get said deadbeat to pay him back as he'd promised he would.