Old thread I know. I'm getting a Win 10 machine and have a Win 7 machine with Sonar 8.5.3 and a lot of VSTs.

Scanning them in the new install will allow those (freeware) that are just .dll files work fine. My issue is more than half probably need to d a full installation, as installing them isn't just about putting a .dll in your VST folder but putting a few other things in System 32 and / or the Registry. 

I learned years ago here (and did it on a prior similar new PC scenario) you can drag the .dll in File Manager  over to touch something found in System 32. I just can't remember what. It worked 90% of the time, saving a lot of time in not having to authorize as much stuff. Help anyone?

It's an old thread, but I was looking for an answer to this question and found something that works the "smart" way on other forums. I wanted to share it here in case someone else get here like me.
 
Typically, most DAW software will search for VST plugins in C:\Program Files\Steinberg\Vstplugins for 64bits plugins and C:\Program Files (x86)\Steinberg\Vstplugins for 32bits plugins. I recommend creating Directory Junction links (or Hard Symlinks).
 
Those are type of shortcuts that emulate a folder that is pointing directly to another one. For example, I installed Z3TA+2 via Steam, so it would be wise to let the dll's in the steam folder if there is updates in the future and prevent breaking anything. So I created a symlink to the steam Z3TA folder. Here's how :
 
1- Launch cmd.exe as administrator
2- Excute the following command: mklink /J Path_to_Place_Link Path_to_Installed_VST
3- Voilà!
 
In my case it look's like this :
For 64bits plugins : mklink /J "C:\Program Files\Steinberg\Vstplugins" "C:\Program Files (x86)\Steam\steamapps\common\Cakewalk\x64\Vstplugins"
For 32bits plugins : mklink /J "C:\Program Files (x86)\Steinberg\Vstplugins" "C:\Program Files (x86)\Steam\steamapps\common\Cakewalk\Vstplugins"
 
I only have plugins from cakewalk so I linked to the whole vstplugins folders but for users that have plugins from other vendor, I suggest created symlinks to individual VST folders like this :
 
mklink /J "C:\Program Files\Steinberg\Vstplugins\Z3TA+2" "C:\Program Files (x86)\Steam\steamapps\common\Cakewalk\x64\Vstplugins\Z3TA+2"
 
This way, you can build your plugins library wihtout disturbing their default folder structure and/or default behavior.
 
Cheers!
 
 

I believe you can just move the folder and change the location in preferences.
No need to enter in any commands / CMD.exe.

Jeez - I vaguely recall that OP's avatar at the top of this thread. 4+ years since he last posted so it's good to know the disturbing memory of it will eventually fade away again.