The growing trend of legal disputes over the unauthorized use of data in
machine learning (ML) systems highlights the urgent need for reliable data-use
auditing mechanisms to ensure accountability and transparency in ML. We present
the first proactive, instance-level, data-use auditing method designed to
enable data owners to audit the use of their individual data instances in ML
models, providing more fine-grained auditing results than previous work. To do
so, our research generalizes previous work integrating black-box membership
inference and sequential hypothesis testing, expanding its scope of application
while preserving the quantifiable and tunable false-detection rate that is its
hallmark. We evaluate our method on three types of visual ML models: image
classifiers, visual encoders, and vision-language models (Contrastive
Language-Image Pretraining (CLIP) and Bootstrapping Language-Image Pretraining
(BLIP) models). In addition, we apply our method to evaluate the performance of
two state-of-the-art approximate unlearning methods. As a noteworthy second
contribution, our work reveals that neither method successfully removes the
influence of the unlearned data instances from image classifiers and CLIP
models, even if sacrificing model utility by $10\%$.