GPLv3 connoisseurs have some simple questions :-)

Suppose program A was licensed with GPLv3. Path then program B was created based on Program A and also with the GPLv3 license. In this new program B there are some possibilities that can be enabled only by activating through the key and for money.

Questions :-)
1. Is it legal?
2. Is the author of program B obligated to completely lay out the source codes of program B?
3. Is it possible to build program B from these source codes, but without any activations?