"Question: Do these children and all their subsequent offspring have to abide by the licensing agreement and pay the company's fees ?"
I say 'no'.
The parents (Joe and Maddy) are the contractees.
The child (John) is the recipient of services (but is NOT a contractee).
John's kids are the benefiters from services (but NOT contractees).
Seems to me: to obligate children (and unborns) to a contract each had no hand in crafting (and had no competency to agree to) is a kind of slavery.
Besides: people are people* and seeds are seeds...
*and Soylent Green