You have assessed the situation correctly: Simply having the disk and 16-digit activation key is insufficient. The activation key is now associated to a specific E-mail account. Within a particular E-mail account, the number of times the software can be activated is limited to five computers that the purchaser of the software owns, which allows for installation on both work and personal computers. Having worked closely with IT with former employees computers, I highly recommend not using work computers for your taxes; too easy for personal information to leak.
