If the library is stored in the "User's Libraries" branch, it is not necessary to do anything, since this folder is shared for all Max instances.
In any case, be sure your libraries are not stored in "C:\Program Files (x86)\Itoo Software\Forest Pack Pro\lib", because this folder would be rewritten if Forest is reinstalled. In old Forest versions it was possible to create libraries here, but now is locked to read only.
You can see the location of each library selecting it and right clicking->Open In Shell. Also it is a good idea to make backup of them.