• by Gavin O'Malley  @mp_gavin, July 6, 2016

So much for ephemerality.

Marking a major shift for Snapchat, the popular messaging platform is slowly rolling out Memories -- a feature for saving and sharing old Snaps and Stories in a private archive.

“It’s a personal collection of your favorite moments that lives below the Camera screen,” the social giant notes in a new blog post.

Users can search through their Memories using keywords like “school,” vacation” or “cat.” Memories can also be used to create new Stories from Snaps that users have previously taken, or longer narratives by combining various Stories.

Snapchat on Wednesday also added a new way for users to send Snaps from Memories, and post them to a Story. Now, if users post a Snap they took more than a day ago, it will appear with a frame around it to designate its historical relevance.

To prevent unwanted sharing, Snapchat also made it easier to move Snaps and Stories to a “My Eyes Only” section.

The change comes amid big shifts in Snapchat’s demographic makeup.

Indeed, comScore estimates that 38% of 25-to-34-year-old U.S. smartphone users are now on Snapchat -- up from just 5% three years ago, which means it's officially breaking into the mainstream.

Of course, the majority of Snapchat users are still relatively young. Overall, about 69% of 18-to-24-year-old U.S. smartphone users are on Snapchat -- up from 24% three years ago.

That said, the new archiving feature will likely appeal to Snapchat’s growing audience of older users.

“Snapchat isn’t showing any signs of slowing down, so I would expect to see them continue to grow their audience across all demo segments,” Adam Lella, senior analyst at comScore, said this week.

“Of course, the 18-to-24-year-old segment is already nearing full penetration, so growth there might naturally slow,” Lella notes. He expects much of the growth from older millennials, 25-34, which has caught on slower than younger millennials, adding it is “an audience that likely has an easier time understanding the product’s appeal (vs. 35+).”

“Meanwhile, “The 35+ segment is the most interesting, as it’s starting to reach a critical mass of users nearing 15% penetration,” Lella added.