Historia Numorum Italy no. 448 is listed with just one legend PROBOM. (P is actually closer to a Π with a short right leg. Note open form of R. These features consistent throughout). A specimen with clearly this legend is illustrated in the plates. Most of the specimens in trade are from different dies with variant readings:
The meaning of the legend is unclear. HN Italy suggests it comes from probus, meaning valid. Although the basic meaning ‘honest, good’ seems fine to me too.
It is connected to a similar legend at Beneventum on a type, the imagery of which is a mirror image of RRC 15/1 (HN Italy 440):
The correct resolution of the legend may be aided by consideration of the variant spellings observed.
Beneventum became a Latin colony in 268 and Suessa in 313. These coins are associated with the First Punic War. Hercules wrestling the Nemean Lion is a common enough artistic theme, known especially at the mint of Heraclea Lucaniae and occasionally at Tarentum.
Addendum. I wasn’t really happy with the probum meaning ‘approved’ as it seemed a strange thing to me to write on a coin. Out of keeping with typical legends (ethnics, magistrates, mint marks, the very occasional labeling of the image). I even tried to convince myself Probus could be an epithet or title for Mercury or something. I didn’t manage. Just a red herring. But … then I remembered the inscriptions on the Egadi rams of a roughly contemporary date.
Egadi 1: C(aios) Sestio(s) P(ublii) f(ilios) / Q(uintos) Salonio(s) Q(uinti) [f(ilios)] / SEX VIROEN[-?–] / probave[re].
Egadi 7: F. QVAISTOR· PROBAVET
Egadi 4& 6 have identical texts: M(arcos) Populicio(s) L(ucii) f(ilios) / C(aios) Paperio(s) Ti(berii) f(ilios) / Q(uaestores) p(robavere)
We’ll known more once the inscriptions are published on there own, but for now the use of the probo, probare, probavi on the rams is enough to let me think probum on the coin is more plausible than I first thought.
[Disturbingly, if you google image search, ‘Beneventum Apollo Coin’, the first image that returns of the coin is hosted on some satanic-esque website obsessed with pentagrams. Reminded me of a time a student of mine unwittingly submitted a project full of images from some awful white power website. Appropriation of the past to support modern ideologies is a dangerous thing, especially on the intertubes.]