Like the custom endocrine systems of combat sleeves in Richard Morgan’s Altered Carbon edit: I think I was thinking of Iain M Banks’ “Culture” series actually, but both are worth a read! Need to be strong or fast? Just give yourself a little squirt of adrenaline! Time for slow heart rate and low energy use? Slow-release a skoche of acetylcholine.
You make a good point about subscriptions. The repo when you stop paying would be pretty grim.
But then they’d have to spend money on shoes to send to Russia, instead of not paying their lawyers!