indentured
adjective
uk/ɪnˈdentʃəd/usrelatingto anofficialagreementthat someone willworkfor someoneelsefor alengthoftime,especiallyinordertolearnajob:
Heservedanindenturedapprenticeshipinmechanicalengineering.
relatingto anagreementin which someoneworksfor someoneelseuntil they havepaidback adebt,especiallyin the past whenpoorpeopleworkedfor someone in anothercountryinreturnfor being taken to thatcountry:
indenturedlabourers/servants/workers