In ye olde boxed versions of AE, Color Finesse did require a key. It was printed on a sheet of stickers. You peeled one off and stuck it in the manual with your AE key.
I've read this while seeking a solution on the web. I thought maybe there still was a serial key available for every Adobe ID that purchased After Effects but the customer support just sent me here (unwilling to help with an issue related to a third-party plugin bundled with AE).
There hasn't been a printed serial number sticker for Color Finesse since CS5.5. The serialization is handled "automagically" the first time you apply Color Finesse to a layer.
That first time you will be asked for a name/organization and you need to enter something there and click OK to cause the serialization to happen. If you click Cancel instead you're left in trial mode with the pink lines. Which is OK, as all you need to do in that case is restart AE and apply Color Finesse to a layer again to get prompted for the name/org.
Once you've done that you're up and running with Color Finesse, without pink demo lines. At that point you can click the Color Finesse About button and see your serial number in the upper right corner of the About dialog. You might want that serial number if you want to upgrade or use an installer from our website.
Now in your case, if you've already uninstalled Color Finesse and run a downloaded installer without ever having run through the "automagic" serialization process, you're left with no serial number and no plug-in that knows how to serialize itself. The best way out of the situation is to un-installl Color Finesse manually, then un-install/re-install AE. You can then apply it to a layer, enter your name/org and you'll be up and running.
And just to be clear, Color Finesse 3 LE that is included with AE is a fully functional/fully featured plug-in. The only restriction is that it works only in After Effects. If you want to also use Color Finesse in Premiere Pro you'll need to pay to upgrade to the "PI" version.
Thanks for replying. I didn't have the time for a reinstall until now. Just finished reinstalling AE and the plugin works perfect now!