@rraud are you sure that (e.g.) NR 2.0 did not come with a previous SF Pro installation?

The NR 2.0 suite has been 'included' with Sound Forge Pro since 8 or 9 as I recall and is still included with the Magix versions... though Magix refers to it as the "Noise Reduction Pack". It is basically identical to the legacy NR-2.0, except for branding and a 64 bit option. It has always been a Direct X plug-in.
Prior to being included with SF 8 or 9, it was an optional purchase. I think the NR suite was first published in the Sonic Foundry days (daze), just prior to the Sony acquisition.

I can see RX 7 Voice De-noise (and other RX7) in "Cleaning" window and Ozone 9 Elements in "effects", but can´t use them ("..no suitable version ); are you sure, that izotope RX7 and Ozone Elements 9 are included in Sound Forge Pro 14, which was part of VP 18 Pro? If yes, how to install/activate?

All versions of Vegas Pro 18.. except .. VP Pro 18 Edit currently include Sound Forge Pro-14
SF Pro 14 includes iZ's RX Elements, as well as the legacy NR-2.0 suite, Ozone Elements and many other audio Fx plug-ins.

Unfortunately, there seems to be a misunderstanding - Ozone Elements is only available as a demo version (as a gateway drug).
Spectrallayers 7 is included in Vegas Pro (not in Vegas Edit).

Ozone Elements and RX Elements are included with Sound Forge Pro and need to be activated through IZotope. I don't think it makes any difference if SF Pro is puchaced separately or is included with VP. Both Ozone and RX have their own serial numbers which are emailed along with the SF Pro info.
'Vegas Pro Edit' does not include Sound Forge Pro.

The IZ plugs are not the full versions, RX Advanced is close to $1k.

Spectral Layers 7 is included (with VPro18), but unfortunately Ozone Elements is not.
At least no key or link was sent to me.
But I think I remember that this has already been discussed elsewhere.

The product pages do list "iZotope Ozone 9 Elements" as included. Maybe there is a "difference if SF Pro is purchased separately or is included with VP".

Personally, I go on the basis that if a bonus add-on is not specifically mentioned in the offer being bought (no matter if that add-on is offered as part of a sales offer elsewhere), then it is probably not part of that particular deal. If it is provided after purchase, then consider it an early or late birthday present.

There is no doubt that a purchase via MAGIX for the full retail version of SoundForge Pro comes with various add-ons that are offered at the time of purchase, but the SoundForge Pro 14 offered as part of a Vegas Pro 18 purchase only says SoundForge Pro 14 - no extras are mentioned. Look at the Vegas Pro 18 comparison chart:

https://www.vegascreativesoftware.com/us/vegas-pro/product-comparison/#productMenu