For connoisseurs of GPLv3, there are simple questions :-)

Suppose there was program A with a GPLv3 license. Way later, program B was created on the basis of program A and also with the GPLv3 license. This new program B has some features that you can enable only by activating through the key and for money.

Questions :-)
1. Is it legal?
2. Is the author of program B obliged to fully lay out the source codes of program B?
3. Is it possible to compile program B from these source codes, but without any activation?