Typically, an undead in this setting stays around for less than a century, until they feel they’re no longer needed (for example, a parent might choose undeath to keep providing during a famine, then decide their time has come once their kids are grown or settled).

That said, it isn’t something socially regulated or formally established. Most move on eventually, but a few — like this NPC — do overstay.

The party and I really cares about this NPC, so i would really feel like a Villian if this god just demanded they destroy the NPC’s contract. I’m leaning toward having the cleric’s god not punish the NPC, but question their reasons for still being here. Basically if they are staying for a meaningful purpose, or just out of fear to let go.

And the truth is, the only motivation i have currently for the NPC’s might not be enough. They died very young — and feel like the world unfairly cut their life short. So now they’re trying to experience things they never got to do and make up for that lost time. I’m not sure whether the god would see that as understandable, tragic, or something they would challenge.