For our hypothetical we set the stage using Second Life as an example virtual world. Second Life is hosted in the United States by Linden Labs. [Terms of Services by Linden Labs][1].

People can upload stuff into the world. Everybody can see items in that digital place if they have access - which is specifically allowed via the ToS in 1.4. People can buy stuff from one another for (indirect) money with up to three of the following permissions via the system: making Copies, Modifying, and Transfering, which is regulated in the ToS 1.5:

> 1.5. You may grant certain Content licenses to other users through the Second Life permissions system.
>
>Your interactions with Second Life may include use of the Second Life permissions system and the copy, modify, and transfer settings for indicating how other users may use, reproduce, distribute, prepare derivative works of, display, or perform your Content in Second Life subject to the Agreements.

Common usage is to buy & sell items CM or MT, or to add a specific usage license to CMT packs that prescribe that you only may give away your modifications with either C or T enabled.

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Alice uploads an item and sells it to others without specifying such a license. Buyers get the item with CM permissions, so can't give them away but have multiple altered copies.

Bob buys the item. For whatever reason, Alice wants Bob to stop using the item.

Obviously, Alice can't buy the item back since Bob doesn't have the Transfer-ability on that item. 

But isn't Alice barred from demanding Bob to stop using her product by the first sales doctrine *and* section 1.5 of the ToS?


  [1]: https://www.lindenlab.com/legal/second-life-terms-and-conditions