Since the emergence of affiliate marketing, there has been little control over affiliate activity. Unscrupulous affiliates have used spam, false advertising, forced clicks (to get tracking cookies set on users' computers), adware, and other methods to drive traffic to their sponsors. Although many affiliate programs have terms of service that contain rules against spam, this marketing method has historically proven to attract abuse from spammers.
Many tools now offer more than one service - you'll find that they each have their own USP but it'll get quite expensive if you have subscriptions to every tool available. We recommend having a good selection of free and premium tools to give you a full 360-degree insight into your target audiences search behaviour and making sure your site is fully search engine optimized.