Even though Google punishes affiliate sites with its algorithm updates from time to time, many webmasters still rely on it to keep their business afloat. If you are displaying affiliate links on your website, you are better off being as transparent as possible with your readers. Affiliate Link Marker is just the WordPress plugin for the job. It lets you mark your affiliate links with a asterisk. It also adds rel="nofollow sponsored noopener" to your links.
This plugin supports Amazon, Awin, Performance Horizon, eBay, and other popular affiliate networks. It not only marks your links but lets you display a disclaimer at the end of your posts. You have the option to add more affiliate domains in the back-end. More information is available here.