Is it permissible to withdraw the money from a fixed-income investment certificate, which was subscribed to before learning of its prohibition, provided that one does not invest in similar schemes in the future?

It is permissible for a person to benefit from money acquired through a forbidden transaction if they were ignorant of its prohibition at the time of acquisition. "So whoever receives an admonition from his Lord and desists, he may have what has passed, and his affair rests with Allah." (Quran 2:275). As for any of these benefits not yet received after learning of their prohibition, they must be disposed of by giving them to the poor and needy, though it is permissible for the needy poor person to benefit from them to the extent of their need. One must cease the forbidden transaction and refrain from investing in it in the future.