We guess you are talking about MiiCraft Builder, right? Please be informed that one licence of MiiCraft Builder can only be registered and installed with one system ID.
For your information, you can still use MiiCraft Suite to do slicing of your stl files, convert the format of the output by “Transfer” to zip file and upload to MiiCraft+ for printing. You can dowload “MiiCraft Suite” and “Transfer” from Support page.
Please let us know if we can provide you further information.