fmtc

The FTC requires that bloggers, affiliates and publishers disclose their relationships with merchant if they earn money 
from links within blog posts. This plugin will add a simple FTC-compliant disclosure statement at the beginning of all 
blog posts.

FMTC Affiliate Disclosure

Add FTC-Compliant Disclosure statement to the beginning of your blog posts

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.

FMTC Affiliate Disclosure vs Affiliate Disclosure for WooCommerce