As it has been stated before around the forum you get a lifetime license including updates to all the modules that are available at the time you purchase the package.
Everything that is released after is sold separately. So yes indeed unless you really need a specific module. It's more economic to upgrade when more modules have been released.
R3C01L
R3C01L,
They've also posted here that if you do a buy or upgrade of the StreamFab product and new modules are added within 30 days, they will license you for it too.
Not sure if this new DRM module falls under this 30 day honoring though, especially with no "upgrade" button in StreamFab after this was added and Buy button next to it (under Licenses) doing nothing.
Mike