WPExplorer

This plugin is an <a href="https://www.wpexplorer.com/best-woocommerce-extensions/" rel="nofollow ugc">addon for WooCommerce</a> which adds a new tab in the <a href="https://docs.woocommerce.com/document/woocommerce-customizer/" rel="nofollow ugc">Customizer Panel</a> so you can enter a custom affiliate disclosure text on your WooCommerce products.
You can enable the disclosure so it only displays on affiliate/external products or on all products. You can also select your placement from several available WooCommerce hooks (before button form, after button form, before button, after button, product meta start or productmeta end), alter the default font size and top/bottom padding.
<h4>Disclaimer</h4>
WPExplorer is not affiliated with WooCommerce, WooThemes, or Automattic. This plugin is provided as a free resource to the WordPress community. We are not lawyers and can not provide legal advice regarding proper site/product disclosures. It is your responsability to ensure you are following proper FTC guidelines.

Affiliate Disclosure for WooCommerce

Display a custom disclosure text on your WooCommerce external/affiliate (or all) products.

jbwagner

The Disclosure Picker makes complying with the FTC blogger guidlines about material connections easy.
In plain English, you can pick from a dropdown on each post or page if you need to disclose affiliate links, review copies, etc. There are 5 different “disclosures”, which are modified versions of the ones in <a href="http://michaelhyatt.com/five-ways-to-comply-with-the-new-ftc-guidelines-for-bloggers.html" title="Five Ways to Comply with the New FTC Guidelines for Bloggers" rel="nofollow ugc">Michael Hyatt’s post on the subject</a>. You can also choose to display the disclosure above or below the content.
The section comes pre-styled with CSS. If your theme uses Twitter’s Bootstrap, it uses the <code>.well-small</code> class by default. The styling will work with or without Bootstrap.

Disclosure Picker

Adds a disclosure, chosen on a per post/page basis, to a post/page either below the content or above the content.

Affiliate Disclosure for WooCommerce vs Disclosure Picker