Easy Digital Downloads - Force account creation for specific price ID

gistfile1.php

<?php

/**
 * Force account creation for a specific price ID
 */
function sumobi_edd_force_account_creation( $ret ) {

	// The 3rd pricing option for a download with an ID of 123 ( 0 = first, 1 = second, 2 = third etc )
	if ( edd_item_in_cart( '123', array( 'price_id' => 2 ) ) ) {
		$ret = (bool) true;
	}

	return $ret;
}
add_filter( 'edd_no_guest_checkout', 'sumobi_edd_force_account_creation' );