Is it permissible for a non-profit organization to charge a nominal fee for Quranic contemplation sessions (majalis tadabbur al-Qur'an) during Ramadan, in order to use these fees to run its programs and da'wah (outreach) activities?

The basic principle is not to take wages for teaching religion, as Allah Almighty says: (Say: "I ask of you no reward for it"). This practice has no basis in the actions of the righteous predecessors, and it may lead to trading in acts of obedience.