24ヶ月（2010年12月以降の利用があるか？）

"MilleMiglia Program" or "Program" means the reward program, lasting from 1 January 2008 to 31 December 2010 and extended by 31st December 2012 and promoted by Alitalia - Linee Aeree Italiane S.p.A. now admitted to the extraordinary administration proceeding ("Former Alitalia") aimed at attracting frequent flyer Clients. As of 11:00 p.m. on 12 January 2009, the Company replaced Former Alitalia as promoter of the Program and shall recognise any Miles accrued,以下略・・

5.19 After a twenty-four (24) month period in which the Member does not fly with the Company or with the Program Partners who help you earn Miles, the Company reserves the right to close the account and void the Miles in the account. The Member is responsible for checking the Miles’ expiry date.
ここでチェックした結果ゼロならば、上記の可能性が考えられます。
5.20 This reward operation allows you to earn Miles until 31 December 2012 (see Article 1.1). The Rewards must be requested by the Member by 30 June 2013. Rewards will be given to those who have the right to them within the maximum period of six (6) months from the conclusion of the operation (by 30 June 2013), pursuant to Presidential Decree of 26 October 2001, nr. 430. The Miles earned and not used by that date will be voided from the Member's personal account.

新生アリタリアでの利用実績がなければ流れる（た）ということでしょう。
マイレージなんか泡みたいなものと思えば、そう深刻にならなくても済むと思うのですが。
私も、多分ゼロになっているはずです（気にもしていない）。