Yes. You can use more than just that one month's premium. But, The deduction cannot exceed the self-employed person’s earned income – after expenses. For example, if you have net Schedule C income of only $1000, your deduction cannot exceed $1000.
Sources:
https://www.healthinsurance.org/faqs/im-self-employed-can-my-husband-deduct-his-medicare-premiums/
https://www.journalofaccountancy.com/news/2012/jul/20126051.html
