Purpose limitation
Purpose limitation is a fair information practices principle, part of the original OECD Guidelines, and a piece of many privacy and data protection regulations such as the GDPR.
The purposes for which personal data are collected should be specified no later than at the time of data collection and the subsequent use of that personal data is limited to the fulfillment of those purposes or such others as are not incompatible with those purposes and as are specified to the individual on each occasion of change of purpose, or for which there is a further legal basis that would not require notification.