Oh no, I'm talking about slavery. It was customary to emancipate after a decade or two of good service, but not contracted or bound by law.
(In fact, if you were a Roman who never freed slaves, you were seen as something of a weirdo. Kinda like, say, a guy who collects thousands of coupons and makes a big deal about it. You were seen as unforgivably stingy and cheap. But there was no law that said you were obliged to free anyone, ever. It was more of a social norm.)
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