I think you're mixing up two different things.
The free keys on the Purchases tab of your profile are for making games you've bought through Caravel available on other platforms (Steam/GOG). That just means you can download and play the game within those platforms instead of using the installers on the downloads page if you choose.
CaravelNet is a separate subscription which provides the online high scores, chat, in-game hold downloads etc., and you're not currently a member. If you bought games through Caravel, you would've received a one-month code in email at the time which you can still use if you haven't activated them (the email has a link, and when you click through it asks which forum account you want to tie it to). Otherwise it's available at $12/year or $4/3months from
http://www.caravelgames.com/buyCaravelNet.html .
Once you're a CaravelNet member, you can get a key from the CaravelNet tab in your profile and use that to activate the online features in each game, regardless of whether you downloaded the games through Caravel, Steam or GOG. Just request a separate CaravelNet key for each game you want to activate (one subscription will issue enough keys to activate online features in all the games, you just can't re-use a single CNet key.)
[Last edited by Tuttle at 04-06-2018 05:08 AM]