We know that M1 includes all the liquid assets like currency,
travellers cheques, Checkable deposits etc, while M2 money supply
includes M1 plus other assets that are less liquid than M1 which
includes money market funds, time deposits, certificates of deposit
etc.
Credit card is not considered as a part of M2, nor it is
considered under any type of money supply because, credit cards are
liabilities and hence cannot be easily converted into cash when
required.
We know that money supply only counts those asset's that can be
easily converted into cash when required, hence credit cards are
not considered as a part of M2.