(MQL4 build 509) From where can I download last stable MT4 and MQL4 platform and how to block any UPDATES?

Having built 509 on your computer wouldn't do you much good. If you connect it to a broker, its going to get updated.

Easiest thing is downloading the old compiler ... you can search for that through search-engines or something.

(You can block the updates - that information is all over the internet - but people on those other sites say that they've been banned from this forum for posting here on how to do things like that. I wonder if even this comment will survive moderation...)

As far as I am aware that isn't the case . . . I towed the company line by suggesting it shouldn't be discussed, but I wouldn't have BANNED anyone for that . . . fortunately I don't have to worry about such things any longer.

No-one got banned within the last thread we had (last time I checked).

It just doesn't make much sense telling people how-to break License Agreements for mt4 on the mt4-forum.

Added: Imo, de-authorizing mt4 from "making changes" comes back to bite users. All of a sudden they cannot save files.

We would also need to teach people the proper manner of using their Operating Systems + the Ethical/Legal Issue.

. . . and that is way beyond the scope of this forum . . .

To be clear: there are reports from people who say they have been banned for posting how to turn off equivalent things, rather than exactly this. I won't specify what they were showing how to disable in case even that is problematic. I have no reason to disbelieve them about being banned, but they don't specify exactly who banned them. The implication is that their accounts were simply blocked, and the posts deleted from the forum, without any sort of "you've been banned" message publicly visible on the affected threads.

Only just noticed that bit. Did you jump, or were you pushed?

Depends who you ask . . . but I requested to jump.

The legal issues are almost certainly beyond the competence of anyone on this forum. Just because a software developer puts something in their EULA doesn't mean that a court would enforce it - in the vastly unlikely event that it ever got that far. A EULA is a sort of polemic designed to give a software developer more rights and fewer obligations than they would have by default in law. For example, I could write in a EULA that you're not allowed to install any competing products to mine on the same computer, but I'd have zero chance of getting a court to uphold that.

Let's make the assumption that this mess is not intentional... ^_^

MQ have not considered the option to set a fee for the stable version of MT4?
(To pay the extra costs for its development.)

I am sure many traders would be happy to pay for stability.