Any document that supports the reconstruction of the trial must be retained at the end of the study. The Sponsor is responsible for archiving all of these documents which are part of the Trial Master File (whose access is strictly controlled). According to the Clinical trial regulation  all clinical trial information shall be recorded, handled, and stored in a way that allows accurate reporting, interpretation and verification, and that the confidentiality of records shall be protected in accordance with the requirements of the General Data Protection Regulation. 
As detailed in the contracts concluded with each centre participating in the clinical trial the documentation produced for the Investigation Site File (ISF) file will be the responsibility of the centre to archive it according to regulations and agreements.