Buying a license

[pokaxperia]

If a buy a product plan (monthly or yearly), that license can be used in any operative system (mac or PC) or only a specific one?

[John Waller]

Mac or Windows or both.

I use my plan on both a MacBook Air and a Windows laptop. No problems.

You'll need recent operating systems on both. 

On PC, you'll need Windows 10. On Mac, either Big Sur or Catalina or Mojave.

[pokaxperia]

But adobe says...

"Why can't I use my software on different platforms?

Adobe develops software for different platforms (such as Mac OS, Windows, Linux) and sells the software built for separate platforms as separate products. If you want to use the products on different platforms, it's necessary to purchase a license of the software for each platform you use. A serial number for a product for one platform cannot be used for the same product for another platform."

https://helpx.adobe.com/x-productkb/policy-pricing/end-user-license-agreements-faq.html

[Peru Bob]

A serial number for a product for one platform cannot be used for the same product for another platform."

By @pokaxperia

That is only for perpetual license software that use a serial number.

Creative Cloud  apps don't use a serial number.

[AxelMatt]

Take a look here: https://helpx.adobe.com/download-install/using/install-apps-number-of-computers.html

There you'll find all informations that you need