You can do a search using multiple tags, as long as there is a query.
I don't think that will work for your case though, but it might get you halfway.
@srinik said in Limit Google Adsense on Signup Pages:
e or limit the Adsense on certain pages of the forum.
I would say you will have to put them in the widgets individual headers for the pages which you only want to show ads on.
Adding in global header is risky.