The HERE Drive app is available for all Nokia Lumia Windows Phone 8 devices. The Nokia Lumia 920, 820 and 620 now ship with HERE Drive+, the Nokia Lumia 520 and 720 will ship with HERE Drive (note no + symbol). It also available, in the HERE Drive version, for non-Nokia Windows Phone 8 devices in select markets.
What's the difference between HERE Drive+ and HERE Drive?
The difference between HERE Drive+ and HERE Drive is the navigation license (i.e. turn by turn instructions) included with the product. HERE Drive+ includes a navigation license for more than 100 countries. HERE Drive includes a navigation license for a single market of region (e.g. UK and Ireland, USA, or Spain and Portugal).
The regional limitations of HERE Drive do not apply to any of the other apps in the Nokia Loction suite. For example, you can still download and use maps for any country in the HERE Maps (including directions), HERE Transit, and HERE City Lens apps.
The license selection in HERE Drive is done automatically and is based on the SIM card in the phone and is done when you start up the app (i.e. it will not matter where you buy the phone). Incidentally, this means you must have a SIM card in your phone to use HERE Drive.
Once HERE Drive has exited beta (expected soon) it will be possible to upgrade HERE Drive to HERE Drive+ (essentially buying a global navigation license). Nokia has yet to disclose how much this will cost, but notes that 90% of use cases are met with a regional license and upgrade prices will be competitive.
You can see more information about the navigation license active on your device in the settings section of the HERE Drive app, as shown in the screen below.