After installing LABS sometimes FL Studio will not locate the plugins.
Firstly, confirm in the file locations listed below that you have a labs(32bit).dll /VST 3 File and labs(64bit).dll /VST 3 file
C:\Program Files (x86)\VstPlugins
C:\Program Files (x86)\Common Files\VST3
C:\Program Files\Common Files\VST3
If these files exist, open FL Studio. (If not, see this article for how to repair a library) Repair a LABS instrument to generate Plugin files.
In the menu bar, click on Options and select File Settings.
A pop-up window will appear showing Browse Extra Search Folders.
Click on a folder icon located beneath the VST Plugins Extra Search Folder and select the install location of your VST plug-ins. (these are listed above)
Once added, click Manage Plugins. (See above screenshot)
Ensure each VST location is in the Plugin Search Path.
Click Find Plugins. (See above screenshot)
After this process, LABS will now show in the Installed section of the Plugin Database.