If you already have an active plan with free app slots, you can add more apps you've built to it. Here's how.
Step 1: Open the app
In your application dashboard, select Manage next to the app you want to add to your plan.
Step 2: Go to publication
In the app editor, open the Publication tab and select Ready? Publish my app!
Step 3: Choose a slot
Pick one of the available app slots tied to your plan, and the app is added to it.
Repeat these steps for each app you want to add.
Why is there an app called "My App (Subscription attached)" in my dashboard?
If you bought a plan before building an app, the system creates an app with your plan attached so the slot isn't lost. You can rename it in the app editor under the Application tab and build from there.