Once in a while we need to renew the gpg keys. Here is how:
gpg --list-keys
will show the available keys, then one needs to
gpg --edit-key xxxxxxxx
then at the gpg prompt we need to call expire and follow the
prompts; choose subkeys with key n, where n is the number of the
subkey to select. Rinse and repeat the expire treatment. Finally
exit with save
If the keys are meant to be published, they should be pushed with
gpg --keyserver pgp.mit.edu --send-keys xxxxxxx