Only paid plans allow you to post adult content such as images. This is the case, because we can not be responsible for the use of adult content in the Free version. If we detect adult content in a website running on the Free plan, we may shutdown your site without notice.
We take this really seriously since it can bring us a lot of problems. Paid plans are responsible for their own content and everything is allowed. We will not be responsible for anything posted in your paid plan.