shouldn't be a problem ;)
but also, when an app (or any other item) from the app store is for a particular version, that doesn't mean it won't work in a 'newer' version. Chances are, you can just open it in a newer version and everything works fine.
When you open a project in your modeler your project gets converted to that version, so if you open a 7.13 project in Modeler 7.16 it gets converted to 7.16 (and vice versa i think? never tried). So keep that in mind..
mendix version selector is espacially introduced to help you choose the correct mendix version.
associate mendix project extension mpr with VersionSelector.exe
Double clicking the mendix project file (myproject.mpr) will automatically start the right modeller version (if installed).
This also happens when a proj has been made with an older version, then you are "forced" to download an older version of mendix and use it :D