What should I do after repenting of violating the internet company’s condition of providing connections to others, and is the device I purchased using this connection considered ill-gotten wealth?

Your breach of the contract terms between you and the company is impermissible, due to the obligation of fulfilling conditions. To repent for this injustice, you must free yourself from the company's claim and pay compensation if you caused it harm. You must refrain from doing this in the future unless the company grants you permission. As for purchasing the device using the receipt, it does not make it unlawful, and you may benefit from it in permissible ways.