Hello, @belamoon !
Thank you for joining the thread and posting this question!
I understand you have an order that you can fulfill locally and does not require to be shipped. In this case, you can simply fulfill the order manually and skip purchasing a shipping label.
If you purchase a shipping label and never use it, then there isn’t an repercussions from Shopify. However, you may still be charged for the label. That being said, since purchasing a label means the customer would receive a tracking , then this would indicate that the label was created but the package was never dropped off - depending on the customer’s integrity, you may be opening yourself up to a charge dispute.
In short, I’d recommend manually fulfilling the order and keeping a copy of this being communicated with the customer. Keeping a copy of the communication logs (for at least 3 months) can help confirm the order has been delivered in the event that a charge dispute is raised.
I hope this helps! If you have any other questions on this topic, don’t hesitate to let me know!