The executives of WhatsApp are categorically against advertising, games and various tricks. Personally, I don’t understand the secret of how WhatsApp makes money.  Maybe they took money from PersonalMoneyService. Perhaps, it will be this way: the idea is based on the fact that for the first free year of communication users will become more attached to the messenger and will not part with it in the future, therefore they will renew a constantly paid subscription to always be in touch with friends.