Starting from Nov 2017, you can no longer purchase the Device Detection service for Sitecore XP 8.1—8.2 from the Sitecore App Center. From this time, Sitecore no longer provides regular updates to the Device Detection database, and the service is considered deprecated.
Upgrade your Sitecore XP solution to Sitecore XP 9.0. All customers using Sitecore XP 9.0 have access to the Device Detection service, with an up to date database available by default. You do not need to purchase the service separately in App Center. You can find more information about the service on doc.sitecore.net.
All existing Device Detection customers on Sitecore XP 8.1—8.2 can continue to use the service, but the device database will not be updated.
The access to legacy devices database stops on 30-Mar-2018, so you must back up a copy of the current devices database on your Sitecore XP solution.
You can find more information about the Device Detection service configuration and the location of the local copy of devices database on doc.sitecore.net.