Honestly. I don't like subscriptions or payments as I only like to pay once and be done with it.
Thus, I don't go for special secure areas.
Also, I always stop 1-2 times on the way home from work (pub/market/etc...), which is where the bike gets stolen.
I just look at the VdS rating of a D-lock that I can fit around my handlebar/in my 20L backpack.
https://de.wikipedia.org/wiki/VdS_Sc...ung#Geschichte
That's VdS (German) and I just simply by a lock they rate as Klasse A+ (best class).
This is the one I roll with:
https://www.kryptonitelock.com/en/pr...ey/000983.html