Straight until the update for Whatsapp IOS arrived. With the new update, new features have been added (storing chat history in iCloud and sending multiple photos), but also a new payment model was introduced. This will change on all platforms, nothing changes for iPhone old customers. These remain of an annual fee spare and keep a temporally unlimited right of use.
Despite some vulnerabilities in the past (here and here to read), WhatsApp is with over 250 million users of the most popular Messenger on Smartphones. WhatsApp cost so far only once a few cents for the app itself. This is changed for new customers now: the provider is the most popular Messenger on an annual payment model, whereby the conditions iOS change not just for Apple, but also for Android and Windows phone 8. The app itself is free, in the future, then likely to, while the Nuztungsmöglichkeit via in-app purchase must first be purchased. Here you can see the prices for the use of WhatsApp Messenger Overview: