UPDATING? On Windows, WAVES plugins use a single WAVES SHELL plugin, that acts as a container for all WAVES plugins. This means that if you have updated your WAVES plugins, or install a new one, you MUST perform a 'Verify plugins' scan in FL Studio with 'Rescan already verified plugins' selected. This is because the the WAVES SHELL plugin is unchanged and so FL Studio does not know something is new there and won't rescan it to discover your new or updated plugins in the shell.
The standard procedure to use Waves plugins in FL Studio is as follows:
In FL Studio, open the plugin selector from the mixer (see image 1 below)
From the plugin selector, choose one of the "waveshell-..." plugins (see image 2)
The plugin wrapper will open showing a selector control, containing all the plugins that are available for that specific "waveshell-..." plugin (see image 3)
Select the plugin you want to load from the selector and it will open (see image 4)
NOTE: that this procedure only works in FL Studio 9 or later.
Networks: Some people have reported that disabling Bluetooth (Ad hoc) networks can solve failure to load issues. It seems that the Waves license center can inappropriately try to use Ad hoc networks to connect to the internet (and fail). These may be created when you connect or tether your mobile phone/tablet to the network through your computer/laptop.
Older versions of Waves plugins don't work in 64bit versions of Windows. The workaround for this is to use a program called shell2vst to wrap the Waves plugins into another plugin. Then most of them will work.