Going by the License agreement, it it appears like mutiple installations are allowed, however it does mention that only one copy can be used at any given time; unless the user purchases enough licenses to match the number of copies they plan on using simultaneously.

I had a look at the software installation and it seems the 'Register' button will only enable itself once a valid serial number is put in. In this case, I would recommend copying & pasting the actual serial number they provided, just in case you happen to mix up certain letters, such as '1' for a captial 'I' or a lower case 'l' or the letter 'O' for the digit '0'.