Is money earned through affiliate marketing via a "content locker" considered unlawful (haram) if the advertisement promises the user something (such as free game currency) in exchange for completing a survey, and then, after completing the survey, the user discovers that the offer has expired or cannot be fulfilled, knowing that the user did not lose money but only lost time?

What the survey company does is forbidden (haram) due to the falsehood, breach of promise, exploitation and deception of the visitor, and the waste of their time and effort without compensation. These are forbidden acts that must be denounced, and assisting in them is not permissible, as Allah Almighty says: ﴿And cooperate in righteousness and piety, but do not cooperate in sin and aggression.﴾ And as the Prophet, peace and blessings be upon him, said: “Deception and treachery are in the Fire.” If an action is forbidden, then the earnings resulting from it are also forbidden, as the Prophet, peace and blessings be upon him, said: “And indeed, when Allah forbids something, He also forbids its price.”