According to a report from Windows Central, the HERE collection of mapping apps have vanished from the Windows Store. The disappearance is apparently not intentional, as a HERE spokesperson has told Windows Central:
We are aware of a technical issue that's preventing us from offering the HERE apps in the Windows Store for new Windows and Windows Phone 8, 8.1 and 10 users. We are working to resolve the problem and restore the availability of the HERE apps for new users. Until it's resolved, we recommend that new users take advantage of the pre-loaded Windows Maps application on their Windows operated device. If you already have the HERE apps on your Windows 8 or 8.1 device, then you should continue to receive updates and see the HERE apps available in the Windows store. Until we have a resolution, we recommend that you do not delete the apps from your device.
Until HERE fixes whatever issue is effecting the apps, HERE recommends new users take advantage of the default Windows mapping apps bundled with each respective Windows operating system. Users who already have HERE apps installed should be unaffected. Stay tuned for more updates on how and when HERE resolves this issue.