If you don’t want to use WHMCS or Woocommerce, you can use Custom Link.
You can use this custom link for affiliate link or whatever link you want.
fill the button text. eg: “Order” or “Purchase Now”.
and fill integration button link with your custom link. e.g: “http://www.namecheap.com/domains/domain-name-search/results.aspx?domain=domain.com&tlds=&searchall=&type=singleidea?aff=XXXXX”
You can use template tag {domain} or {sld} or {tld} to include domain/sld/tld in the link. e.g: “http://www.namecheap.com/domains/domain-name-search/results.aspx?domain={domain}&tlds={tld}&searchall=&type=singleidea?aff=XXXXX”
Also, to disable integration, just select integration with disable.
