How Long Do Retail Stores Have to Press Charges Against Shoplifters

My question involves criminal law for the state of: MA

Assuming you were never caught (for stealing, say, under $50 worth of merchandise), if the store you stole from happened to find out about what you took through CCTV/surveillance, how long do retail stores have to come after you? Assuming they can only go off your debit card info.

I've read many places that MA's SOL is 6 years, but in others I've read that stores have 24-36 months.

They have until the SOL expires.

Where are you coming up with "24-36 months"?

Realistically speaking, unless you get caught stealing again, the odds of a complaint being filed a year or more after the fact are very slim.