It's hardly adware is it. Nothing to get so upset about. It's simply a prompt to show there's another version out there which the programmers put a lot of time & effort into whilst you're sitting there using a free version. Using the free version hardly merits any complaints about a simple link. Besides there's no dramatic differences between the 2 versions.

Likewise if there's a newer version available you'll also get a prompt. It's not exactly advertising in that respect. It's a request to keep the gnutella up to date & using community accepted versions & not out of date ones that do the gnutella community damage.