Remember that the next life is divided into the contemplative disembodied heaven and the active embodied paradise.
The distinction is necessary because our union with and mastery of the material world is essential to our very nature.
The activities in paradise will be of two types: production and consumption.
What sort of things will be produced? Those which you will learn in heaven how to build. An example would be games of astonishing realism and excitement. It is possible that this world is precisely one such game.
Now as regards contemplation, there will be no use for free will: God will teach you those things that He chooses of His own counsel. You will receive knowledge from God in much the same way as a cat receives food from your hand. This will be fun but not involve your own choosing what to study.
As regards production, there is quasi-freedom. Jesus, acting as a “central planner,” will assign to you — perfectly enjoyable — work that He knows you would have chosen yourself had you been able to see fully into the infinitude of your own and your fellow saints’ everlasting lives.
You are no cat this time: God will not interfere or help you with the work in any way: you and others will do everything yourselves.
There are several reasons for this. First, God does not need any external goods; He is already perfectly and infinitely happy. Second, the effects of charity, St. Thomas argues, are union, mutual indwelling, ecstasy, and zeal. You will work on producing things even without a desire to use them personally, because your love for neighbor causes you to feel the neighbor’s joy as if it were your own. You will have zeal to labor for the beloved’s sake. Finally, a pride of achievement and honor in active life may be an incentive; and “labor” will not be physically taxing due to “replicators” and suchlike.
(The only disutility attached to work will be its opportunity cost: while producing, one refrains from contemplating or consuming. But then of course everything whatsoever has such a cost. It’s the essence of freedom to pick one thing to enjoy at the cost of setting aside inferior choices. What I suggest will be eliminated is the tedium of labor rather than its cost.)
This supplies us with one crucial reason why the perfection of charity and trust for God are so important. The paradise economy cannot be a command and control system imposed on unwilling slaves for all eternity and enforced with a whip. The “socialism” will be based on charity and flawless divine foresight not coercion.
As regards consumption, there will be full freedom as to which amenities of paradise, including “games,” you will want to enjoy.
In this life, free will acquires a final meaning not present in the abode of blessed: the freedom to choose between good and evil.
There is metaphysical evil, because it was impossible to make the highest-ranking embodied creatures — rational animals with minds mixed with matter — who make or complete themselves such that they would not be subject to corruption.
In paradise, choosing evil is impossible, but at the expense of progress. Only in this life can we improve so as to enlarge our capacity for true happiness. (The flip side is that we can also get worse.) In the afterlife, whether permanently or temporarily, that capacity is fixed.
Thus, in paradise you will not be free to choose to murder another saint, because the idea will never occur to you. (If it could, together with a malicious feeling and temptation, God, foreseeing that, would never allow you into paradise in the first place.) Of course, you would likely know a great deal about murder purely speculatively: even angels whose nature is pure and who have merited glory are fully aware what evil can lurk in the hearts of men; you will be, too, even in paradise. But you will have complete freedom to decide whether to play soccer or StarCraft 2.