Remove Messages from Navigation and Add Friends, Private Message and Public Message from BuddyPress profiles if current user or profile viewed does not have a Paid Membership Pro member level

jmw_remove_buddypress_messages_for_non_ppmpro_members.php

<?php

add_action( 'bp_init', 'jmw_remove_buddypress_messages_for_non_ppmpro_members' );
/**
 * Remove Messages from Navigation and Add Friends, Private Message and Public Message from BuddyPress profiles
 * if current user or profile viewed does not have a Paid Membership Pro member level
 */
function jmw_remove_buddypress_messages_for_non_ppmpro_members() {
	global $current_user;

	if( function_exists( 'pmpro_getMembershipLevelsForUser' ) && function_exists( 'bp_displayed_user_id' ) ) {

		$current_user_levels = pmpro_getMembershipLevelsForUser( $current_user->ID );
		$displayed_user_levels = pmpro_getMembershipLevelsForUser( bp_displayed_user_id() );

		if( empty( $current_user_levels ) || empty( $displayed_user_levels ) ) {
			remove_action( 'bp_member_header_actions', 'bp_add_friend_button', 5 );
			remove_action( 'bp_member_header_actions', 'bp_send_public_message_button', 20 );
			remove_action( 'bp_member_header_actions', 'bp_send_private_message_button', 20 );
			bp_core_remove_nav_item( 'messages' );
		}
	}
}

Needs more testing. For example what if the current user or displayed member used to have a membership level?

pmpro_getMembershipLevelsForUser() will return an array of level objects so maybe you could check for expired levels? I'm away from the desk so can't check what those level objects contain