If you already have your OpenPGP public key published on Public key servers, then make sure to update its Revocation status/Expiration date there (each time you modify it) by using this feature.
- Go to Settings -> Messages -> Encryption and click on your OpenPGP key pair under My Personal key.
- Click on Publish on public key server.
- This will publish your OpenPGP public key on SKS based key servers (https://sks-keyservers.net/overview-of-pools.php).
Note: This is a non-reversible process. It will also publish your display name along with your associated email address that you will not be able to delete or modify. However, this will allow other users to find your public key easily.