In a post on its developer news site, Apple has announced that the iAd App Network will be closing down on June 30. While Apple is no longer accepting new apps into the network, developers can still run campaigns through June 30. From Apple:

The iAd App Network will be discontinued as of June 30, 2016. Although we are no longer accepting new apps into the network, advertising campaigns may continue to run and you can still earn advertising revenue until June 30. If you'd like to continue promoting your apps through iAd until then, you can create a campaign using iAd Workbench. We will continue to keep you updated, but if you have any questions, contact us.

The iAd platform was first introduced in 2010 as a way for developers to easily place ads in their apps. The announcement of iAds impending closure follows a report from earlier this week that claims Apple is planning to move to a fully automated system for publishers and advertisers in the future.

Source: Apple