I don't believe it will. When they installed VS they probably installed the Enterprise edition. When VS tries to validate the license the next time (which can be a little while) then it'll determine they are running an edition they aren't licensed for and prevent them from using it. They will need to install VS Pro. Fortunately you can have both installed at the same time (although I don't know why you would) so they can install VS Pro, get it set up and then uninstall VS Ent. The downside is that the VS Installer (which installs both) won't let them have any edition of VS running while uninstalling but should be fine for installs.
VS 2019 and VS 2017 I believe work the same way. I don't remember about VS 2015.