Kendall Jenner and Devin Booker celebrated their one-year anniversary this summer

Kendall Jenner and Devin Booker are continuing to spend quality time together.

On Wednesday, the supermodel, 25, and the NBA star, 24, hit up a rooftop party for Jenner’s 818 Tequila at the Sunset Beach Hotel on Shelter Island, where they toasted the success of the new liquor brand alongside friends such as Karlie Kloss, Derek Blasberg, Luka Sabbat and Fai Khadra.

“They were laughing, playing around with each other and kept making eye contact throughout the night, and never stayed far away from each other,” a partygoer tells PEOPLE, adding that Booker seemed “very close and friendly” with Jenner’s pals.

“At the end of the night, they walked out together hand in hand with nothing but smile,” the insider says.

Guests were previously asked to take a COVID-19 PCR or rapid test within 48 hours of the get-together, regardless of their vaccination status, and to bring a proof of a negative result to the event, according to a party source.

Jenner and Booker were first linked in April 2020, but the pair didn’t make their relationship Instagram official until this past Valentine’s Day.

At the time, the Keeping Up with the Kardashians alum shared a sweet photo on her Instagram Story of the twosome cozying up.

“She is crazy about him. She has never looked happier. Her whole family loves Devin too,” a source told PEOPLE in June about the couple, who had celebrated their anniversary this summer.

“Devin is such a cool guy. He is very low-key and doesn’t want to be a celebrity. He is very sweet to Kendall,” the source shared.

Earlier this week, Booker gave fans a glimpse of how he and Jenner have been spending their time together since his return from the Tokyo Olympics, sharing a picture of the model lounging on a boat wearing the medal he earned as a member of Team USA’s basketball team.

“LAKE BOi,” Booker wrote in an Instagram post, which also featured a snap of Booker floating in the lake, as well as a shot of his dog on a boat.