There would no need. 9.1 reached end of support a while ago, and we work only with 9.5 onward. Either way, LR 9.1 was not designed to work on 64 bit OSes in mind, but Windows 2008 will allow the install and if there are problems running you can try using it in compatability mode that Windows allows.
For migrating, just install LR on the new OS and then add the license, but the license if it is bound to a host ID will require you to get a new one.
Regards,
Mario M.