Alexander Romanov has long-term stability on Long Island now, having signed an eight-year, $50 million extension with the Islanders two days before free agency opened this summer.

The 25-year-old defenseman is not using that as a reason to let his attitude slip.

“Obviously so happy,” Romanov told The Post before skating in his first preseason game of the year, a 6-2 loss to the Devils Tuesday night . “But you got to prove that you’re responsible to play at this high level for the next eight years. We’re not only talking about this year, next year. All eight years.”

And what, exactly, does that mean on his part?

“Just play hard,” Romanov said. “Hardest hockey I ever played. Go all out.”

Alexander Romanov looks on during a break in an Islanders’ practice earlier this month. Corey Sip

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