The Hilton HHonors Windows Phone app, which offered users travel planning features and special access for HHonors members, is slated to be retired in the near future.
The Windows Store page for the app states:
IMPORTANT MESSAGE: We'll be saying goodbye to the HHonors Windows Phone app soon, but you can still find all our great travel-planning tools and your HHonors member benefits on the Web. We'll update you with more details here soon.
The company announced the retirement of the Windows tablet version of the Hilton HHonors app earlier this year. There's no specific information on when the Windows Phone version will be shut down.
Thanks to Paul for the tip!