And why would you want to run Pro Tools 12 specifically? To run Pro Tools 12.5 or earlier? There has been a lot of enhancements and bug fixes to Pro Tools since then. I'd want to be on a recent (like 2021.12) release if my OS supported it.
Some retailers might still have the now expired promotional program licenses to sell. The program expired December 31st. I would call Vintage King (strongly recommend them) or Sweetwater and ask them. This is exactly what to ask for:
https://www.pro-tools-expert.com/hom...until-31st-dec
Otherwise subscriptions are an option if you don't want to repurchase another perpetual license.
A good sales rep at a reseller can understand your needs and walk you through all options.