You should only list your long-term medications. These are prescriptions that you will be taking for the foreseeable future.
If you anticipate taking your prescription for more then three months this would be considered "long-term". A "No Re-fill" prescription is NOT a long term and should not be entered. Example: An antibiotic (in most cases) is a short-term treatment and should not be listed on the card.
In the frequency section of that medication, just simply indicate "AS NEEDED." Example: Nitroglycerin (NTG) is typically taken only as needed.