Can plants flower at certain point regardless of time?

Will plants flower even if the light is above 12 hours if they've gotten to old? Outside that is.

if its an autoflowering srtain yes

As far as i know, if its a outside plant, it will flower with the season. If it has long light days then it would stay in veg for very long time, alot of people keep mothers for a long time in 18 hrs

Some plants may flower anywhere between 12/12 and 15/9 (or even 16/8 depending on the strain and the climate it was breed for. Unless an autoflowering plant, a plant won't flower until the light/dark ratio hits the magic number that's written in its genes.

There are 3 varieties of Cannabis: C. sativa, C. Indica, and C. Ruderalis. The Ruderalis is what gives the auto-flower capabilities. However, since Ruderalis (pure) is not very potent, they cross it with potent strains to give a better autoflowering product.