I sent you an e-mail earlier concerning the API key's usage, but decided what the heck, and figured I'd find out myself and it seems the key isn't site dependant, which is great.
I've went ahead and included a BotScout lookup in my Spambot Search Tool (I use this on multiple sites for multiple forums/forms/blogs/etc)
Welcome, and thank you for implementing the API in your software!
You're correct, the API key is not site-dependent; you can use the same API key on as many sites as you need to. Currently the key is good for 300 API queries a day, but we can adjust that up if you need more (just let us know).
We're almost ready to release our Bot Trap Form Server, and you're more than welcome to use that as well. We're putting the finishing touches on it and hope to have it available within a few days.
The Form Server lets people put a small line of code in a page that invisibly embeds a randomized form in the page each time it's loaded. The form is very attractive to bots and is designed to be nearly impossible for them to identify as a bot trap.
Unfortunately, the Form Server system needs a different key for each site registered; this was a design consideration forced on us in order to prevent malicious users (botnet owners) from poisoning the database. We don't have a hard limit on the number of sites allowed yet, and the limit will be adjustable on a per-user basis, so trusted users will be able to deploy more forms than other users.
The system uses a scoring ladder to help weed out false entries, and should be very effective in proactively responding to bots and letting them add themselves to the database.
If you're interested in trying out the Bot Trap Form Server, let me know and we'll get you going. It's very easy to implement.
Again, welcome and thank you for implementing the BotScout API in your code!