Hello skiph,
You must have downloaded and run EtreCheck about two weeks ago. EtreCheck it will display a single notification two weeks after you generate a report. That would explain the notification and the fact that you have 4 reports available. Tech support via web discussion forum is a new concept to most people. If people are having a problem bad enough to download and run EtreCheck, I want them to follow up and see if the problem is still there or has been resolved.
Unless you have disabled Apple's Gatekeeper security system, it is not possible for EtreCheck or any other app to download and run itself. You would have to physically double-click on the app and then confirm with Gatekeeper that you downloaded it and want to run it. Only then would it actually run. EtreCheck does not install or move itself. If it is no longer where you downloaded it, you must have moved it. EtreCheck is designed to be a temporary app and can run from any location.
EtreCheck is free to use. Obviously you have already used it once for free. It is designed to be used to generate 5 reports for free. That should be enough to identify the problem, work through solutions, and confirm that the problem has been resolved. After that, you can throw it in the trash. But if you like what it does, you can choose to pay for it and keep using it.
As for your "unauthorized posts" problems, there are a few of possible causes:
1) Apple is currently re-writing the forum software. Since the forum is huge and can't be shut down, they are doing that while it is running. Sometimes it just flakes out. This is a regular annoyance for regular users.
2) Your post could have been removed. If this happens, you should have an e-mail message from the Apple hosts explaining why your post was removed.
3) You could have replied to another post that was removed. If this happens, you won't get any e-mail about it. When the Apple hosts remove a post, that removes all replies to it. This is the internet and sometimes people just go off the deep end. The hosts are very good at cleaning up messes.
I looked at your other thread and I don't see the reply that was quoted above. It looks like something was removed. I wouldn't worry about it. People have a tendency to lose their inhibitions and decorum on the internet. Even though this site ends in "apple.com", it is still just another publicly-accessible forum on the internet. Sometimes the Apple moderators' skill at cleaning things up does a disservice to how nasty and potentially dangerous the internet can be. You have already unnecessarily revealed some personal information in this thread. That is a bad idea.
I'm sorry I didn't see your concerns sooner. I can assure you that EtreCheck has nothing in common with MacKeeper or other "clean up" apps. EtreCheck just reports what it finds and never makes changes*. (*If you ask it to, EtreCheck does remove adware and clean up some partially removed and non-functional files).
I will add another reply to your original thread that may shed some light on your original problem.