Ok thanks alot

Not a problem, the only time it doesn't work is if the content is moved or re-downloaded to another console. If that's the case, you have to use this licensing tool on the xbox site to license it to the new system but you really don't want to do that unless you plan on using that system exclusively.
In the case that you do download it on another xbox, your account will have to be logged in and signed onto xbox live for it to work without being licensed.