OP, before you send anything I want to look at this: This is on a road where I actually live, and therefore have a visitor permit which I often use,
Next is this: .. however this time I forgot to pay
As I understand it, 'visitors' permits' are for the use of 'friends and guests of residents' not residents themselves. But maybe I'm wrong and you should know. But if not, then IMO don't reveal that you live there if you want them to exercise discretion.
Also, do you normally pay or do you display and why 'pay' on this occasion?