You can create a key when activating your account or at a later time.
Things to know
A key for the application is used for the security of your documents. The key for the application works similarly to a key for a safe where you keep important documents. So only you are allowed to view or edit the documents in the safe. The safe is protected with your password. In this way, only you yourself have access to the encrypted documents.
In your application, the key is a mere technical function to additionally encrypt particularly sensitive documents. Only you can view, download or edit the encrypted documents with the password for the key.
You can, of course, turn off the encryption of your document again. You find a manual under Reversing Encryption. Turning off the function only affects new documents.
Security is important
Keep the password and the corresponding key file safe. Be sure to download your key file. You find a manual under Downloading the key to reset the password.
If you nevertheless forget your password for the key, you can reset this password using the key file only. You find a manual under What do I have to do if I forget my key password?