GYDÉ is a gas giant that is wholly owned by the Praxille Corporation.  Its industry is concerned with the extraction of pharmaceutical chemicals from the planet's atmosphere, and this work is done entirely by automated machinery.  The most important end-product of these chemicals is the life-extension drug "Senolyte".  It is fantastically expensive to create, but for fantastically wealthy individuals, each dose increases the chance of surviving another year to about 99%.  The oldest known Senolyte patient is over 300 years old.  In orbit around Gydé, watching over the robotic workers, are two space stations with two supervisors each.  To compensate for the boring and isolated duty, each supervisor is supplied with Senolyte.  Often the pairs are mated or at least good friends.  Even so, rumors of murder-suicides have been reported.  Hence the backup station to ensure that Praxille maintains uninterrupted occupation of the planet's orbital space.

Hmm. If you're young, there's little attraction.

So I imagine the Senolyte supervisors are typically seniors, or had life-threatening diseases when they first took the job.

Now they are living roughly as long as they can stand it. If they leave, do they resume their natural lifespan based on the age they started? Or the age they left? Or do they just crumble in a matter of days? At what point is it worth it? How many have stayed for decades just to spite their co-supervisor?
Very little data is available on human Senolyte patients who have voluntarily ceased treatment and subjected themselves to normal aging. Developmental trials suggest that years of life would probably remain, but not a full "lifetime", as Senolyte appears to slow but not stop the aging process. Many life-threatening diseases are not "cured" by Senolyte, however, so a patient with only "weeks to live" would probably succumb to the same disease even sooner.