Burlington software maker Aspen Technology Inc. will open a new office in Nashua on Tuesday, marking a long comeback for a company that several years ago was in deep financial and legal trouble.
The expansion is to accommodate a growing workforce, which is 1,325 worldwide and more than 400 locally, and Aspen will use the Nashua location for a regional research and development center.
The 31-year-old company, founded by a Massachusetts Institute of Technology professor, makes software that some of the biggest names in the chemical and oil industries, such as Exxon Mobil Corp. and The Dow Chemical Co., use to manage their sprawling production processes.
Aspen’s revenue in its most recent fiscal year was up 23 percent, and it recently hired about 100 people, many of whom will work out of the renovated, 41,ooo-square-foot facility in Nashua, once occupied by defunct Massachusetts minicomputer maker Digital Equipment Corp.
Just a few years ago, Aspen was on its back, with revenues plunging nearly in half and its stock delisted. The former chief executive was convicted of securities fraud, and its founder charged with falsifying revenues.
It survived in part because of a tough round of cost cutting implemented by chief executive Mark Fusco, who took over in 2005: The company shed about 300 employees and closed nearly one-third of its offices around the world.
“I wasn’t well liked around here for awhile,” said Fusco, a former professional hockey player who became chief executive a year after he joined the board as a part of a $100 million investment into Aspen by the Boston private equity firm Advent International Corp.
Fusco replaced former Aspen chief executive David McQuillin, who after leaving the company was convicted of securities fraud in 2007 for falsifying revenues.
McQuillin was sentenced to three years of probation and fined $12,000.
Aspen’s former chairman and founder, MIT professor Lawrence B. Evans, was also charged in a civil lawsuit by the Securities and Exchange Commission with falsifying revenues.
He settled the case and is no longer involved with the company.
In 2010, Aspen was relisted on the Nasdaq; since then, its stock has climbed from around $9 to a 52-week high of $26.33.
It closed Monday at $24.87, down 3.75 percent.
Aspen grew out of a project at MIT that was partially funded by the Department of Energy to create modeling software for the oil and gas industry.
It was led by Evans, who taught chemical engineering at MIT and served as Aspen’s chief executive until 2002.
“All their technology is fundamental to some of the biggest companies in the world,” said Dick Hill, an analyst at the ARC Advisory Group in Dedham.
The new facility in Nashua is Aspen’s fourth research center and its 27th office worldwide.
The office will serve as a center for development work on the company’s core software products. It will house up to 150 employees.
The expansion “is a statement about building for the future, which is different from what we would have be talking about seven years ago, which is turnaround,” said Fusco.
Evans, 77, has continued to watch the company closely even though he is no longer involved with Aspen.
He would not comment on the regulatory issues that involved him and the company, but said that he never thought the business was in a dire position.
“I never had any concerns that the company would not be successful,” he said. “Aspen is basically a household word in the chemical and petroleum industry.”