I don't know if currently some installation over the current one is supposed to delete the chest.
If the content of the chest is not there anymore, there is no way to recover it.
Whatever the case, it is clear to me that you are confussing the (renewal of the) registration for the Free edition of avast with something else.
The registration, or the renewal of it, is performed from avast main GUI -> maintenance -> registration. It is usually a very simple procedure, with the possible exceptions of the server temporarily not working, or for offline systems. For such cases, the offline registration is also available.
The free registration is required for the Free edition once a year. The updates will not be performed if the registration is not valid and current. No additional download is required to register nor to renew the registration of avast Free edition.