The Bekenstein bound says if a volume of space has access to a finite amount of energy then the amount of information necessary to describe it is also finite, and that implies Bremermann's limit which says there is a maximum rate of information that can be processed in that volume, and it works out to be c^2/h= 1.4*10^50 bits per second per kilogram of mass/energy. However I think it should be possible, at least in theory, to extract work out of the expanding universe (see next paragraph), and if the expansion of the universe is accelerating then it seems to me the amount of energy you could have access to in that volume of space could potentially be infinite, not finite.
Suppose you had 2 spools of string coiled in opposite directions connected by an axle and you extended the 2 strings to cosmological distances 180 degrees apart from each other. As long as the Dark Energy force between the atoms in the string that were trying to force them apart was not stronger than the attractive electromagnetic force holding the atoms of the string together the string would not expand as the universe expanded, so there would be a tension on the strings, so there would be torque on the spool, so the axle would rotate. The axle could be connected to an electric generator and you'd get useful work out of it. Of course you'd have to constantly add more mass-energy in the form of more string to keep it operating, but the amount of mass per unit length of string would remain constant, however because the universe is accelerating the amount of energy per unit length of string you'd get out of it would not remain constant but would increase asymptotically to infinity. If the theories about the Big Rip turn out to be true and the acceleration of the universe is itself accelerating then it should be even easier to extract infinite energy out of the universe, provided we take care to continually shorten the string to keep it from breaking. So it would all just be a simple case of cosmological engineering. What could go wrong?
And If you have infinite energy then you can perform an infinite number of calculations, so you could have an infinite number of thoughts, so you would have no last thought (the definition of death), so subjectively you would live forever. Of course the objective universe might have a different opinion on the matter and insist that everything including you had come to an end, but that hardly matters because subjectivity is far more important than objectivity; or at least it is in my opinion.