When you register an app it stores that info on your hard drive, often in a hidden fashion based on the idea that hiding registration info makes it harder for someone(s) to develop a crack, which is basically a method of registering the software so it'll work without paying for a license.
If the registration info is stored in the program's folder, it's accessible to anyone or any account on that PC/laptop -- if you install the app to the default Program Files [or Program Files (x86)] folders you may need to run as admin to register since it often requires elevated privileges to write to those folders, e.g. in win7. Note that a few apps store their registration info in Windows' system folder, which also requires elevated privileges to write to. If the registration info is stored in the user account folders, e.g. C:\ Users\ [UserName]\ AppData\ ... in Vista\7\8, or in the User sections of the registry, only the account(s) where it was registered can access that data -- in those cases the app should be installed/registered for every account where you plan on using it. Also, writing to the registry [e.g. to store registration data] may require elevated privileges [i.e. run as admin] depending on the version of Windows & the type of account, while certain sections of the registry require elevated privileges Always.
Now, software doesn't always behave the way we think it should. Some apps need to be set to always run as admin in win7 64 for example, while other apps will not run properly that way -- in either case "not running properly" may or may not include reporting that the app's not registered. And some few apps will not run properly on more than one user account -- their DRM might be keyed to whatever files/data installed to the user account, and either limited to one activation or simply won't work with two or more sets of user-based data.
And finally, even when the registration &/or activation data is there, one of the app's processes has to check it, & if that process doesn't run the way it should, it'll report that app is unlicensed. Particularly in win7 or 8 64, Usually it's a good idea to run any newly installed app as admin the 1st time, especially if you're trying to run it in an account other than the one where it was installed. That allows the app to write any needed files &/or registry entries so every part of it, including the license checking, runs as it should [note that I said that *Allows* the app to write that stuff, but that doesn't mean that every app will].
At any rate, long story short you just have to take each app as it comes, & use whatever methods work with or for that app -- programs don't all behave the same way so there's no one, universal method that works 100% of the time.