The Disable Clickjacking Protection feature can be found under Memberium > Settings > Security:
This setting is toggled to No by default meaning that Memberium will implement measures to protect your site from clickjacking.
What is Clickjacking?
According to owasp.org, “Clickjacking, also known as a ‘UI redress attack’, is when an attacker uses multiple transparent or opaque layers to trick a user into clicking on a button or link on another page when they were intending to click on the top level page. Thus, the attacker is ‘hijacking’ clicks meant for their page and routing them to another page, most likely owned by another application, domain, or both.”
They go on to give an example: “Imagine an attacker who builds a web site that has a button on it that says “click here for a free iPod”. However, on top of that web page, the attacker has loaded an iframe with your mail account, and lined up exactly the “delete all messages” button directly on top of the “free iPod” button. The victim tries to click on the “free iPod” button but instead actually clicked on the invisible “delete all messages” button. In essence, the attacker has “hijacked” the user’s click, hence the name “Clickjacking”.”

How does Memberium prevent Clickjacking?
There are several ways to stop clickjacking. The primary method is by setting something called X-Frame-Options Response Headers. This header is set by your website (or Memberium in this case) and it tells the web browser whether or not it’s allowed to embed your site into another site (via and iFrame).
Since clickjacking relies on embedding your site via an iframe into a malicious site, by instructing the browser not to allow your site to be embedded, you’re guarding your site against this attack.
Memberium sets the X-Frame-Options header to SAMEORIGIN.
Where can I Learn More?
Although Memberium has you protected as long as you leave this setting on – if you want to learn more Upguard has a good blog post explaining what clickjacking is, common attacks, and how to defend against it which you can read here.