TypeError: __init__() missing 3 required positional arguments

[snippsat]

TypeError: __init__() missing 3 required positional arguments: 'MemberName', 'MemberID', and 'SubscriptionPaid'

As you have it now NewMember=JuniorMember('Ali', 4444, True)
Set default arguments,the can use it like this.

class JuniorMember(Member):
    def __init__(self, MemberName='', MemberID='', SubscriptionPaid=''):
        super().__init__(MemberName, MemberID, SubscriptionPaid)
        self.DateOfBirth = ""

    def SetDateOfBirth(self, Date):
        self.DateOfBirth = Date

Use:

>>> NewMember = JuniorMember()
>>> NewMember.SetMemberName("Ali")
>>> NewMember.SetMemberID("12345")
>>> NewMember.MemberID
'12345'
>>> NewMember.MemberName
'Ali'