Let me go through a year for you and clarify:
Buying a ticket on Jan 1, then Feb 1, Mar 1, etc. The twelfth ticket expires 31 Dec after 365 or 366 days
Buy a ticket on Dec 31, then Jan 31, Feb 28 or 29, Mar 28 or 29, Apr 28 or 29, etc. The twelfth ticket expires on Dec 27 or 28 after 362...