Any trick to avoid Sonar from asking for keygens in plugins every time a project is open?

need mo info. What plugins? If you register the plugins, they usually stay that way.

A little vague for a direct answer. WRT plug-ins which require registration, I run SONAR as administrator and never had a problem with plug-in registration. Never had a plug-in ask for authentication more than once.

It happened with albino3, I changed the folder (dll, content, and banks all in 1 folder...) and now it´s ok. Now it´s happening with novation Bass station too..., sometimes with waves SIlver bundle too.
Dont know why...

There are no keygens required for a legal copy.

Sometimes the registration process doesn't complete correctly unless you're running Sonar as Administrator. But this is only the case for plugins that you have to register by opening them in the host, e.g. Waves has its own License Center. I have my Waves license on a USB stick and it will check for it whenever I open a Waves plug, and otherwise just ignore it.
 
If you can't get your Waves license to stick I suggest taking it up with them, since it's a process completely separate from Sonar.

The term "keygen" is only for pirated software, one would hope you just used the wrong term. 

Cactus Music
The term "keygen" is only for pirated software, one would hope you just used the wrong term. 

 
Ye olde 'Freudian slip'...
 

I doubt SOnar is asking for a keygen.  As already stated, unless it was just a mistake, keygens are usually for pirated software.  Even if they are legit copies, SOnar would not be concerned about any "key" for a third party software.