Is the questioner obligated to pay money or donate it as expiation for using pirated software and distributing a pirating tool that led to its widespread use, especially since he cannot delete the post or limit the number of users? And will this sin remain open against him even after his death?

The door of repentance is open, no matter how great the sins and transgressions against the rights of others. The questioner should increase in good deeds and charity, and supplicate to Allah to appease those whose rights have been violated. He should also try to contact them and seek their forgiveness or reconciliation if possible, and strive to remind people to safeguard rights. There are no "ongoing sins" in the sense that the door of misdeeds remains open after repentance.