You would be immortal and all basic amenities essential for physical survival would be provided. You can have the age of your body according to your choosing and your mind won’t blow off by accomodating endless amount of memory.
You can choose anything you desire and that too at any instant which may or may not exist in real life, like an endless supply of something or a companion with the same immortality powers as yours, but you won’t be able to change it in the future and there would be no going back. Also you cannot alter your mind in any way that would enable to let you tolerate living for eternity or not get bored of things.
Ideally you would want to have everything just to be sure but by asking you the minimum requirements, it would making it more interesting to know what you think you could do without or what matters to you the most.
Infinite supply of breathable air
Otherwise the post stellar era is gonna start sucking for you real bad real quick
We’re talking end of JoJo’s Bizarre Adventure Part 2 level “ooooooooof” in terms of how much suck you’re signing yourself up for, floating in an abyss lit by ghosts of long dead stars and galaxies, not having been able to take a breath in trillions of years and yet also not being able to die from suffocating because of it either.
There is a reason why only half of that level of shit to be in was referred to by the Supernatural fandom as “Turbo Hell”
Wouldn’t that fall under the basic necessities part of OPs post?
I would ask for a means of travel in with this as well… fixing the lack of breathable air would be pointless if you’re stuck aimlessly drifting through space, Bender a la Godfellas style.