On concrete5.org, go to-
->'My Account'
-> 'Projects' (Found on the right sidebar)
-> Select the project you'd like to assign your add-ons to (Click on the 'Name' of the project; not the 'URL')
-> Now you're on the project page; scroll down to the very bottom of the page where you'll find your add-ons
-> Now you can- "Add an add-on or theme to this project by selecting it from the list below, and clicking "Associate."
"

If you aren't seeing them on your transactions log:
https://www.concrete5.org/profile/bank/...

Or on your licenses page:
https://www.concrete5.org/profile/orders/...

Then you likely used a different user account to purchase them. I'll follow up with you off the forums to see if I can help you sort it out.