a question that is in my mind for quite a while already: When and under which conditios can I make sense to constraint yourself (even if there is NO budget-constraint) in order to maximize your utility?
If it was consumed in previous periods, it keeps providing utility, but less than in previous periods - because the consumer gets saturated (the technical term is marginal utility).
This is false.
Contrary to a typical spending function, the consumer is indifferent between consuming the apple today or tomorrow.
This directly contradicts Austrian theory.
utility function
utility is ordinal
whether a free good should always be consumed, or if it might make sense to abstain from consumption under certain circumstances.
Confusion of terms. Rothbard makes it clear that consuming an item today and consuming an item at some other time can very well mean that you’re not consuming the same good. Like his example of “ice-in-the-winter” and “ice-in-the-summer.” See MES.
I don’t know what your background in economics is, but maybe consider Lessons for the Young Economist, followed up with Rothbard’s Man, Economy, and State.