Why Not Just Use Popular Music in Your Production?
In order to use a popular piece of music from the latest charts (or even a golden oldie) in any production, you need to obtain permission from the copyright holder in the form of a synchronization license.

It can be a long, tedious and expensive process to get permission to use a popular song. If you can't live without a particular song, be prepared to search for and negotiate with the composer or publisher and the performers and owners of the recordings. You will find that some music is virtually unobtainable: the artist may not want to be viewed as endorsing a product or idea, or the musicians' union may have placed restrictions on reuse of the song outside of the entertainment field. And even if you are able to get permission to use the song, it may well be unaffordable.

While obtaining a synchronization license for a popular piece of music is quite an expensive proposition, keep in mind that using the music without the proper license in place will leave you open to liability for copyright infringement and other actionable claims under international copyright laws. That will cost you several times more than the original license fees would have cost.

Music that has been around for years may still be covered by copyright and may not be in the public domain. Seventy years after the composer's death (not the publication of the music) is the norm for many countries; some have even longer copyright protection periods. Even if a piece of music is in the public domain, you do not have the right to use an already published version of the song; the rights to that version belong to its publisher. Essentially, you would need to publish your own version of the song: either by recording it yourself or by hiring someone else to do it for you. Either of these options can also be expensive. To complicate the public domain issue further, a later version of a composition or the addition of lyrics can even change the status of a piece of music that was in the public domain - it may move back into the copyright category because of these changes.