WooCommerce Attach Me GPL Overview:

1. attach files to products (like manuals, documents, etc.): these files are automatically available to download in the product pages and/or on order details page after the customers have purchased them (and optionally visible only if the order has reached a specific status)! You can also specify an Expiring time (only for order attachments)!
2. create automatic email attachments: sent when a specific order status email is sent by WooCommerce