Most music DLC's say something along the lines of "Can be used in any RPG Maker Engine of your choice".
Some even go one step further and allow you to use the Music outside of RPG Maker products.
Here is an example from "RPG Maker MV - Modern Day Music Mega-Pack Vol 03" by Joel Steudler:
(Taken from Steam)
* This pack is for use in RPG Maker Series or the engine of your choice.
* OK to be used in Commercial projects
* Contents can be edited
* OK for use in games with gore
* OK for use in adult-rated games
* Royalty free music to use in your commercial and non-commercial projects.