agorakit/agorakit

use App\User;

class UserPolicy
{
    //
    public function create(?User $user)
    {
        return setting('user_can_register', true);
    }
    //
}

use Illuminate\Foundation\Support\Providers\AuthServiceProvider as ServiceProvider;

class AuthServiceProvider extends ServiceProvider
{
    protected $policies = [
    \\
    \App\User::class             => \App\Policies\UserPolicy::class,
    \\
  ];

    public function boot()
    {
        $this->registerPolicies();
    }
}

use App\Http\Controllers\Controller;
use Gate;

class RegisterController extends Controller
{
    //
    public function showRegistrationForm()
    {
        if (Gate::allows('create', User::class)) {
            return view('auth.register');
        }
        else {
            abort(500, 'You cannot create an account on this server');
        }
    }

    public function handleRegistrationForm(Request $request)
    {
        Gate::authorize('create', User::class);
        //
    }
    //
}