Microsoft Bing announced they are shutting down the Bing Ads Express service because their customers need more granular controls when managing search campaigns.
The service is being shut down on July 30, 2014 and there seems to be no migration path from those running ads on Bing Ads Express to normal Bing Ads.
On July 30th, we will sunset the Bing Ads Express product, and will offer search marketing opportunities to our customers only through Bing Ads. Until this time, any current or past Bing Ads Express customer will be able to access their account information. After July 30th, customers will no longer be able to access their account information.
Customers can continue promoting their business across Bing, Yahoo and partner sites by signing in at Bing Ads with their existing username and password. Once logged in, customers will need to create a new account and go through the campaign creation process. To help with any questions or sign up process, customers can reach out to Bing Ads Support Team. For customers that choose to setup a new account on Bing Ads before July 30th, they should pause their Bing Ads Express ads to avoid running duplicate ads and being double billed.
Here is a video on Bing Ads Express:
Forum discussion at WebmasterWorld.