If you are having issue with activation in Studio One, first trash the Plugin Alliance folder in: %USERPROFILE%\AppData\Roaming\


Then, go ahead and delete the Studio One Preference files in the following folder: C:\%USERPROFILE%\AppData\Roaming\PreSonus\Studio One 3\x64


Look for the following files to delete:

PluginBlacklist.settings

Plugins-en.settings

VstBlacklist.settings

Vstplugin.settings

After doing this, go ahead and reboot Studio One and you should be able to reactivate your plugins without any issues.