I might be able to read Portuguese because I am Portuguese, but these forums are mostly in English, and so is the language most support people understand here.
No, each release of PD has a 2 year product support lifecycle which includes updates to the program including the ability to work in new versions of OS X that come out during that time. If your PD version works with the latest version of OS X even thou it's outside its lifecycle of support you are under no obligation to buy an upgrade.
For instance, PD 9 is still under the 2 year support lifecycle and you don't need to upgrade to PD10 to work with Yosemite, you only need to upgrade to PD10 if you want any of the new features.
