Nothing in this world is free, even theoretically.
The nuance relies on whether ownership of the machines is applied.
I'm strictly talking about the most basic of necessities - housing, food, clothing, transportation - from the point of view of the recipient, which is basically all human beings who received without working for it.
It issue at hand is perspective. It may be free to someone but not so to others. Free is defined as receiving something that wasn't obtained by effort or energy. That's why you have people exclaiming, "I got this for free!!!"
There is always a cost to satisfy a need or want, that much I agree with; however, cost is borne in different ways as well as by whom at any scale. It can be monetary, energy, resource, etc. Cost is relative. The party perceiving the cost doesn't necessarily have to be human especially when we add a new class of intelligence capable of mimicking what we've been doing to help ourselves survive and even more.
It is possible for the self-replicating machines to bear the cost of their activities but it's "free" for the humans under certain conditions. It's always a balancing act, and yet it is not necessary to have humans on both sides. This has never been done since the dawn of humanity until now (I mean until when we entirely depend on the machines for food, housing, clothing, etc.)