The use of Copernicus Sentinel Data is regulated under EU law (Commission Delegated Regulation (EU) No 1159/2013 and Regulation (EU) No 377/2014). Relevant excerpts:

Financial conditions

Free access shall be given to GMES dedicated data [...] made available through GMES dissemination platforms [...].

Conditions regarding use

Access to GMES dedicated data [...] shall be given for the purpose of the following use in so far as it is lawful:

GMES dedicated data [...] may be used worldwide without limitations in time.

Conditions regarding information to be given by users

1. When distributing or communicating GMES dedicated data [...] to the public, users shall inform the public of the source of that data and information.
2. Users shall make sure not to convey the impression to the public that the user’s activities are officially endorsed by the Union.
3. Where that data or information has been adapted or modified, the user shall clearly state this.

Absence of warranty

GMES dedicated data and GMES service information are provided to users without any express or implied warranty, including as regards quality and suitability for any purpose.