All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If the credit card used in commercial transactions involves Riba (interest and/or usury), then it is forbidden for a Muslim to use it, because Riba is forbidden, be it little or much. Allaah Says (what means): {But Allaah has permitted trade and has forbidden interest.} [Quran 2:275]
Allaah also Says (what means): {And if you do not, then be informed of a war [against you] from Allaah and His Messenger. But if you repent, you may have your principal-[thus] you do no wrong, nor are you wronged.} [Quran 2:279]
Moreover, Ibn Mass'ood narrated: "Allaah has cursed the one who consumes Riba (i.e. usury or interest), the one who gives it to others, the one who records it and the one who witnesses it (its transaction).” He said: "All of them are equal in sin.” [Muslim]
As for your statement that this card helps in many business transactions, then this does not render it permissible. A person resorts to dealing with Riba in case of necessity but the necessity is not a sound reason for making Riba permissible.
As regards the ruling of studying in the university with Riba, it has the same ruling as the ruling on transactions with Riba, meaning that they are both forbidden.
Allaah Knows best.