HELP PK contains a new rule (yes yes, I hear the collective groan).
Luckily, this one is very simple: You aren't allowed to take revenge
against someone for something that person did more than 30 (real-world)
days ago. Thus, if Bob killed you 2 months ago and you haven't gotten
around to taking revenue, you'll just have to deal with it.

Exceptions can be made for truly exceptional circumstances. For
instance, someone ripping off all the gold from a city or guild would
definitely warrant some extended punishment by the city/guild members.
Events that we would consider exceptional circumstances are very very
uncommon, however, and you would be best to clear it first with an
admin, keeping in mind that the fact that Bob killed you a bunch of
times when you were a newbie is not sufficient reason. Nor is Bob having
been a pain-in-your-ass a year ago, etc.

Penned by my hand on the 8th of Scarlatan, in the year 299 AF.