I bought a website about 6 months ago, SEO was done on it about 2 years ago. At the moment I am still high ranking in most of the keywords I want. There has been no SEO done on it for 2 years but now I am starting to worry about my ranking. It hasn't dropped yet but is it possible that it will start dropping soon? I am not sure why its still high ranking but I am worried that if I start SEO on it now, it will firstly have a negative effect and I will never get back to the ranking I was. I just want to leave it but I am not sure if this is the best thing to do.