Under the GDPR one way to use data for purposes unrelated to the underlying service provision is to look to obtain consent. That is not opt-out consent but clea

Under the GDPR one way to use data for purposes unrelated to the underlying service provision is to look to obtain consent. That is not opt-out consent but clear informed consent through opt-in. If your service won't work functionally without certain data then consent is not right ground of processing to rely on. There is a specific ground relating to processing necessary to provide a service. If your service isn't financially viable because you can't use data to obtain revenue to support the underlying service provision then consent may not be a viable ground because of the above reasons. The debate continues however on how to support free service provision outside of the confines of consent.