As we mentioned in the beginning, most the advertising services nowadays require you to pay them monthly. As soon as you stop paying, the advertisement stops and so does traffic to your website. However, in the case of SEO, you only have to make the initial investment. His makes investing in SEO much more economical than going for other alternatives like sponsored advertisements.
SEO is not the only free source of driving traffic to your website. If you are smart enough and you have a well-devised plan, then you can share and spam social media sites. The link would drive a few people to your website, but that is a one-time thing. Every time you want people to visit your pages and website, you will have share vigorously to get the attention you wanted. IF you invest some initial time on the SEO ranking of your website, you would hardly need to do any social media marketing. People will come by their own volition.