Does using a program loaded onto a device with a fake serial number, knowing about it later, constitute a sin that necessitates accountability?

It is not permissible to use pirated software because it infringes upon the rights of its owners. However, if one is unaware that the software is pirated, there is no sin upon them. The sin falls upon the one who deceived them. They must cease using it and pay its value to the company for the period they used it, if they are able. Otherwise, they should give charity equivalent to its value, because ignorance nullifies the sin but not the obligation (guarantee). It is better to stop using such software altogether.