Many products and organizations are named using initials, often the initials of an owner or founder, or of a former business name. I recently hired an exterminator which game its name simply as "RPC" but their literature indicated this stood for 'Ron's Pest Control". The company IBM was once International Business machines, and 3M was once Minnesota Mining and Manufacturing.
One risk is that in using a TLA (three letter abbreviation) you are not likely to be unique, and may be confused with very different products or firms with the same initials. But that is mostly a business risk, not a legal risk. If another firm has trademarked the initials you want, that might be a problem. But you can't copyright a short phrase such as a title, much less a three or four-letter designation. For Example "APL" is both the name of a shipping company (American President's Line) and a programming tool (A Programming Language). Most such letter designations have multiple meanings already assigned.