Does every campaign have its own tracking code?

The answer is no.

When subscribing to a plan you'll get an individual customer id, which will show in your tracking code as well. No matter the amount of campaigns you've created, they will all run by the same tracking code.

Therefore, you will just need to implement the tracking code once in order for your campaigns to appear on your website.

Also, if you have more websites, the tracking code will still be the same, all you need to remember is to implement the tracking code once at each website and you'll be good to go.

The following is just an example visualize what the tracking code looks like. As you can see, every account has a specific customer id.