@Vincent-Cairns
You can subscribe only to the navigation part of the app. This also gives you access to the Here map in the web planner, allowing you to create routes based on the Here map. However, you'll miss out on all the very handy tools that the toolkit offers, especially for the demanding planner. Are you a demanding user who wants to get the most out of route planning? Then I recommend subscribing to both the planner and a Gold subscription.
On the other hand, if you only navigate with a dedicated device like a TomTom or a Garmin, you might find that a Gold subscription alone is sufficient. After creating your route, you would then need to export it to your device.
If your BMW also have Apple CarPlay or Android Auto, you can stream your route to your BMW right from the navigation app (you do need a subscriprion to the navigationpart of the app if that's your case).