The integration of 1&1 E-Shop which is a part of 1&1 hosting is done by direct insertion of the sale tracking code to a special section designed for affiliate tracking code.
You can track total cost, order ID, customer email (for Lifetime Commissions) and currency.
Navigate to eBusiness> 1&1 E-Shop> Settings> Cart settings> Texts> Affiliate-Tracking-Code section and
If you want to track a currency as well, use placeholder #CurrencyCode
Save your changes and you are done. The site just has been integrated.
Do not forget to integrate your site with the click tracking code to make it all working. You can do that in Slogan section of eBusiness> 1&1 E-Shop> Settings> General settings> Presentation - just enter the code to the code section (icon with page and <> symbols) of the Slogan area.