WooCommerce - Disable purchase for non-logged-in users. (Remove add-to-cart button).

functions.php

<?php
// Do NOT include the opening php tag.

// Disable purchase for non-logged-in users. (Remove add-to-cart button).
function m3wc_woocommerce_is_purchasable( $is_purchasable, $product ) {
	if ( ! is_user_logged_in() ) {
		return false;
	}

	return $is_purchasable;
}
add_filter( 'woocommerce_is_purchasable', 'm3wc_woocommerce_is_purchasable', 10, 2 );

// Show "Login to see prices" instead of price for non-logged in users.
function m3wc_woocommerce_get_price_html( $price ) {
	if ( ! is_user_logged_in() ) {
		return '<a href="' . get_permalink( wc_get_page_id( 'myaccount' ) ) . '">Login</a> to see prices';
	}

	return $price;
}
add_filter( 'woocommerce_get_price_html', 'm3wc_woocommerce_get_price_html', 10, 2 );