Is it forbidden for me to listen to lectures by a specific professor via group subscription, given that a single lecture costs a sum of money that I cannot afford to pay on my own?

The fatwa issued is that intellectual property rights are protected for their owners, and it is not permissible to infringe upon them. Therefore, if a teacher prohibits the copying and distribution of lectures to non-subscribers, it is not permissible to do so. However, some scholars permit copying for personal, non-commercial use, and there is no harm in acting upon this opinion. As for listening to a lecture at a subscriber's location without copying or distributing it, it appears there is no harm in that.