There is no limit to the number of accounts one can create. However, instead of creating separate accounts for different websites, it is advisable to have all your sites under one account since there's no limit to the number of sites you can have in a single account.
If you have many websites, you could also use the grouping feature, which allows you to classify or categorize all the websites in one account, based on separate clients or similarity of themes. You can create separate groups under which to list specific types of websites. This allows for easier management of the sites in your account.