Hugely popular mobile messaging platform WhatsApp is looking to make some changes to its pricing structure in the coming months. The service is currently free for the first year and then costs users a $1 yearly recurring fee, except on iOS where a single upfront payment of $.99 is required. But moving forward the company will switch to the subscription model as standard across all mobile platforms.

WhatsApp CEO Jan Koum revealed the plan to Dutch journalist Alexander Klöpping, saying that while there’s not set time frame for the change, it will definitely happen in 2013. When asked why the company was making the change now, Koum simply said they wanted "to keep things simple.”

It’s important to note that the new pricing will only apply to new users. Those who have already downloaded WhatsApp on iOS can continue using the service for the foreseeable future without the recurring charges.

Koum was also asked about a desktop client for the service but the CEO says they’re staying mobile-only.

WhatsApp passed 100 million downloads on Google Play in November and has remained among the top paid apps on Apple’s App Store in 119 countries for quite a while. The company has kept mum on actual download numbers per platform, but recently announced they’re serving 17 billion messages per day (7 billion inbound, 10 billion outbound). That’s up from 1 billion daily messages a year ago and easily bests iMessage’s 2 billion milestone revealed in January, which should give you an idea of the service’s reach.

Despite this -- or perhaps because of this -- WhatsApp has been heavily scrutinized and criticized for their inadequate security practices. Only as of August 2012 the company started encrypting messages sent over Wi-Fi and mobile networks. They’ve since addressed other issues related to authentication as well.

Free cross platform alternatives to WhatsApp include Line, GroupMe, Facebook Messenger, among others.