entended form 2.6
Click here to go to your licenses pagehttps://www.concrete5.org/profile/orders/...
Find the add-on in question and see if a license is available or if it is still assigned to the dev environment. If it has a details button there click it to see what domain it is currently assigned to.
If your add-on is available or you have made it available go to your projects pagehttps://www.concrete5.org/profile/projects/... and assign it to the project you want.