Apparently "going concern" is a common term that laymen understand. It is not jargon.
It's common enough that it's been used as the title for a pop animated sitcom episode -- Archer (S2E2).
For example, "we bought the business as a going concern" would be its use in a typical sentence.
My gut feeling is that these days the phrase is used more commonly in the vernacular in the UK than the US, with US usage being much more restricted to the pure 'business' professions (e.g. managers, accountants, etc), and not so much elsewhere.
Common day-to-day usage to express same would tend more towards more nebulous or incorrect terms as 'successful/profitable business' or perhaps 'liquid/insolvent', or something like that.
It's definitely "business speak", but I'm surprised anyone with a job like programming doesn't know it. Prior to this, I would have assumed that basically anyone would know the phrase.