When a new version of JMP is published to My JMP, you can update your existing installation in place. This means the installation file can be used as an update on top of what you already have installed.
Launching jmp__18xx__win.exe or jmppro__18xx__win.exe when JMP / JMP Pro 18 is already installed presents the following dialog:

Choose Modify to begin the installation of v18.x.x, overwriting the older version.