Depending on the situation it might be very obvious (they republish it after the deletion request) or you might not know without examining their system directly

Depending on the situation it might be very obvious (they republish it after the deletion request) or you might not know without examining their system directly. There are a number of options depending on the context. If Tent ends up like email (90% of users spread across a handful of service providers), then one term of the license could be consent to regular audits by mutually trusted individuals or organizations (e.g. the EFF).