Hi Nan Sun
you can change the PC and therefore also the license where it is ACTIVATED, but it depends on the actual license ACTIVATION on the particular PC, therefore if you set that license is activated until the END of it duration ( full 3 months ) on one PC, you cannot switch it to another one in that time. Best if you set it for 7 days and when it ends, you can switch it to another PC, or another Windows installation on the same PC ( if the OS is different ).