One of the GDPR's principles of data processing is storage limitation. You must not store personal data for longer than you need it in connection with a specified purpose.

Data Erasure and Storage Time The personal data of the data subject will be erased or blocked as soon as the purpose of storage ceases to apply. The data may be stored beyond that if the European or national legislator has provided for this in EU regulations, laws or other provisions to which the controller is subject. The data will also be erased or blocked if a storage period prescribed by the aforementioned standards expires, unless there is a need for further storage of the data for the conclusion or performance of a contract.