Shamim's Plugins

You can follow https://www.shamimsplugins.com/support/topic/allow-only-admin-to-message-groups/#post-36544
Or if you want to allow multiple user role users to send group message you can follow https://www.shamimsplugins.com/support/topic/question-about-groups-messages/#post-28661 (change roles as you want)

1. May be other user blocked him or does not want to receive message
2. You can set a larger limit or 0 if no limits

You can cancel auto-renew from your account page in https://www.shamimsplugins.com/account/
You will get automatic email 1 month before license expiry to renew manually.

Please add following code in your theme’s (child theme’s if you are using) functions.php

add_filter( 'fep_current_user_can', function( $can, $cap, $id ){
    if ( 'access_directory' != $cap || ! is_user_logged_in() || fep_is_user_blocked() ) {
	return $can;
    }
    if( array_intersect( [ 'administrator', 'editor' ], wp_get_current_user()->roles ) ){
        return true;
    }
    return false;
}, 10, 3);

Thank you.
It seems your forms get submitted before we get a response from google with keys.
I need some time to fix this issue.
If you are in a hurry and want a refund let me know.

I can check when it is active. Do you have any staging site for this website? Or can you make a test site with this same settings for testing?

May be someone from that message has blocked you.
You can add your username in the whitelist in Front End PM PRO > Settings > Security, That may bypass that check.
Let me know.