Last year, HERE Maps - originally created by Nokia, and later sold to an automotive consortium - disappeared from the Windows Store due to a "technical issue". The app returned to the Store earlier this year, but it will soon be removed again - and this time, for good.
HERE announced today that it will be removing all of its apps, including Maps, from the Windows 10 store later this month [emphasis ours]:
In the last few months, we made the HERE apps compatible with Windows 10 by using a workaround that will no longer be effective after June 30, 2016. To continue offering the HERE apps for Windows 10 would require us to redevelop the apps from the ground up, a scenario that led to the business decision to remove our apps from the Windows 10 store.
This means the HERE apps will no longer work on devices running Windows 10 mobile after June 30, 2016. To prepare for this change, we have also decided to remove the HERE apps from the Windows 10 store on March 29, 2016.
HERE apps will continue to work on Windows Phone 8 "without any disruption" beyond that date, as the company notes that "HERE is deeply integrated" into that version of the OS. However, it also points out that it has "made the business decision to stop the development of new features... [and] the maps developed specifically for Windows Phone will not be updated".
Future development efforts on Windows Phone 8 will be limited to "critical bug fixes" only.
Source: HERE