|The stupid question is the question not asked|
For clarity... IntelliJ IDEA which is what this plugin is geared toward is completely free, as is their PyCharm offering specific to Python development, but this plugin works there as well (I have a devel VM where I have a Perl/Python mix). It also works in CLion which is their C/C++ IDE. That one is not free. All of their IDEs are essentially the same look and feel wise, and all of them have configurations that can be moved around between them.
In saying that CLion isn't 'free', that's kind of a misnomer; I in fact have a "free" license for all of their software, thanks to their Open Source licensing program. Essentially, you send them a request to use their software, and provide evidence of your Open Source work as justification for this yearly renewable license.
At work, we use the fully licensed version of PyCharm. For my Open Source work, I used the free IDEA for Perl. I then went on a hunt for an IDE for C that would hook into the Arduino platform and found CLion. Looking around for a "free" IDE that would suit my needs, I came across this particular licensing opportunity. In my request, I stated that I only needed that IDE, but the license came with everything they have to offer, and because of a software management platform they have, all aspects are installable and upgradeable through a single interface.
Between this answer and the one I'm replying, that should provide everything anonymonk requested.
Combine this configuration with the Vim plugin, and you've got a powerhouse of a Perl development environment.
In reply to Re^3: Perl5 plugin for IntelliJ IDEA 2017.1.2 released. Perl 5.26 support and more