Can you see if I register in the FritzBox?

So my problem is this:

I recently copied the Wi-Fi password from the neighbors' FritzBox for my laptop. Now my question: Can you see whether I'm in it, is it shown whether who is logging in and do I somehow put more costs on their necks or can you not see my laptop at all?

You can see on the fritzbox which devices are connected to the Wi-Fi.

But whether you notice that is another matter. This does not result in additional costs for them. But get your own internet, or at least ask if you can use their internet…

If the neighbor knows his way around, he can see your device.