What is the ruling on buying stocks using someone else's card if it was gifted to me, and what is the ruling on buying them using my family members' cards?

Subscribing on behalf of another person has two scenarios:

1. For a fee: This is not permissible. 2. Without a fee (as a donation): If the company's regulations prohibit it: This is not permissible. If the company's regulations do not prohibit it: There is no objection to it.