So, using combination of email address and cookies gives SellShareware high probability of crediting affiliates when they deserve. Affiliates would recognize this hole in the system, and would chose products that they are sure to get credit for. Costs, Features, and Getting Started. This is the same thing. The more you offer, the more affiliates will sign-up and work hard to sell your product.
Some authors are a little short-sighted and complain about giving up even a dollar of a sale.
This type of thinking will hold back the growth of your business. Your product has already been created, so it costs you nothing to have another user with it. If you can make anything off an additional sale, it is worth doing. Also keep in mind, your affiliates program doesn't affect any of your other distribution or sales, so affiliate sales will be in addition to your normal sales. It is a no lose proposition.