The law simply requires that the content recommendation algorithm not be shared between the two apps. [0] Thus, it must be rebuilt by the new team, and not maintained or controlled by the old team.

The licensing approach is a temporary solution to keep the app working from day 1. One of ByteDance's complaints during the lawsuit earlier this year was that is was going to be technically infeasible for engineers to rebuild something as complex and essential as the content algorithm in the short window of time they had before the law went into effect.

[0] https://www.congress.gov/bill/118th-congress/house-bill/7521...

"The term “qualified divestiture” means a divestiture or similar transaction that ... would result in the relevant foreign adversary controlled application no longer being controlled by a foreign adversary; and ... precludes the establishment or maintenance of any operational relationship between [the two apps/teams], including any cooperation with respect to the operation of a content recommendation algorithm or an agreement with respect to data sharing."