FORTUNE -- For Evernote, the digital note-taking app co-founded by 41-year-old CEO Phil Libin, the last five years have been pretty damned good.
Since Fortune profiled the startup in Fall 2011, Evernote has more than quadrupled its users to 66 million -- 2 million of whom pay -- moved from a one-floor Mountain View office to a Redwood City-based building with 320 employees, acquired at least five startups including the Mac drawing app Skitch, and released a slew of new features including Evernote for Business, currently used by over 5,000 companies. Evernote has raised $251 million in funding from T. Rowe Price, Sequoia Capital, Morgenthaler Ventures and others, as it invests heavily in expansion. <!-- ?xml version="1.0" encoding="UTF-8" standalone="no"? -->
"If you're vastly profitable, it kind of means you've run out of ideas," Libin tells Fortune. Indeed, the St. Petersburg-born, Bronx-raised serial entrepreneur has long said he views Evernote as a "100-year company," one that with the potential to endure that long because it's in the business of the storing memories: it lets users type documents, take photos, save Web stories, record voice memos, among other things. The data are stored on the company's servers and accessible on users' desktop and mobile devices. So, an interview recorded via Evernote on an iPhone is almost immediately available to listen to with Evernote for the desktop.
Libin suggests there's much more to Evernote than just note-taking. (Going public is not something the company plans to do for at least another two or three years.) Libin talks of a new "super-sexy encryption" feature -- his words -- tentatively due later this year. More interesting: he has an internal team designing hardware products that expands the Evernote experience.
One current product line that offers an idea of what Libin is talking about are the traditional Moleskine notebooks designed in partnership with the startup, with page materials that ensure capturing clean digital shots snapped by Evernote for the phone or tablet.
"We designed it at the same time we were designing the digital experience around it," explains Libin. "So some of the new things are going to be electronic devices, and some are just going to be just [physical objects] that aren't necessarily electronic, but are designed together as a complete experience. But they're all about making you smarter, giving you elegant ways of being productive."
Libin argues tech is returning to a point where design is thought of again holistically, pointing to Apple (aapl) as the most obvious example, as well as products like the Nest thermostat and Fitbit. "The world right now is on the verge of a revolution of massive design thinking," says Libin. Clearly if Libin has his way, Evernote will have a large role in that.