It manages more than $11 billion in revenue for its customers.
Financial proclamations by Internet companies—both public and private—are replete with references to “recurring revenue,” often generated in the form of subscriptions or other ongoing relationships. Which begs the question: what systems are they using to manage billing?
Historically speaking, many telecommunications companies, media organizations, and other businesses heavily reliant on subscribers have cobbled together their own software for sending billings and accounting for incoming payments.
These days, however, a wider spectrum of companies is establishing ongoing customer relationships requiring a different approach to collecting payments. Some illustrative examples: services for replenishing supplies (à la the Amazon Dash model) or for managing predictive maintenance agreements.
Software concerns seeking to capitalize on that need include well-funded Zuora, which has raised approximately $250 million since 2007. Another rising company is Aria Systems, which last week disclosed a $50 million Series E funding round. The infusion brings the 14-year-old company’s total backing to $133 million.
“Aria has the best solution for enterprise organizations that are saddled with slow and expensive legacy systems that can’t deploy recurring revenue initiatives quickly and efficiently,” said Lars Leckie, managing director at venture capital firm Hummer Winblad Venture Partners, one of Aria’s repeat backers.
Aside from Hummer Winblad, Aria’s return investors are Bain Capital Ventures, InterWest Partners, Venrock, and VMware.
Get Data Sheet, Fortune’s daily technology newsletter.
Aria’s software manages both ongoing contracts, including subscriptions for software and other services, as well as one-time sales that are repeated often, such as digital downloads for applications or mobile transactions such as renting a piece of equipment for a discrete period of time.
Last year, the platform processed more than 200 million transactions. Aria’s customer list reflects many different models. Auto company Audi, for example, uses Aria’s software to run billing for its car-sharing initiative. (Zipcar uses it for similar purposes.) Philips Healthcare uses it to manage the pay-per-use program for its medical imaging equipment, and car sales site Edmunds.com uses Aria’s technology to run its billing operations. Other big customers include software purveyor Atlassian team and streaming media service Roku. Aria’s customer retention rate is 97%, according to a senior executive.
Aria CEO Tom Dibble said the majority of his company’s new funding round will be dedicated to scaling customer support operations. While his company’s average contract length is four years, the length of time is growing. Simply put, billing systems are long-term investments. “When we sell to large companies, they expect certain levels of services,” Dibble said.
Aria currently employs about 300 people, a large majority of which are dedicated to research and development support and creating application reference architectures, he said. The San Francisco-based business has approximately 150 customers.
Aria, Zuora, and SAP’s Hybris division lead the pack of software companies providing systems capable of handling large volume subscription or usage-based billing models, according to a November 2015 report published by Forrester Research. Among them, they manage almost $300 billion in subscription revenue for their customers, the report suggested. “These three vendors represent thought leadership and the associated market innovation,” the Forrester analyst wrote.
Among Aria’s strengths are its ability to install its technology quickly, as well its technical partnerships with Netsuite, Oracle, SAP, and Salesforce. It manages about $11 billion in billings, the report estimated.