I guess if you really want to make sure to keep your 11.1 version working you can do so with a few simple steps

1. make a backup of your activated Licence go to C:-ProgramData-Poser-11 and backup this folder in case it gets corrupted or deactivated
2. go to C:-Windows-System32-drivers-etc there you will find the "hosts" file open it with a text editor
3. add that line on the bottom 127.0.0.1 my.nalpeiron.com then save the hosts file this will make sure that Poser will not call home and prevent the conflict of activation check same result as if you were offline the old version is setup to call the smith micro host and this method should make sure that poser will not cause an error when trying to call home and cant reach the host.

Like I said I assume that it will work and this way you may be able to keep your version as loong as you wish having it or until your projects are done without risc