Javier, we don't have Premium here but I would hope the license's work the same way. If you go to the help tab and select "SolidNetWork License Manager" you should be able to borrow the Premium seat as long as it is not currently in use.
Javier, yes the laptop will only be able to receive the license it has been installed with. If it was installed with the SW Standard serial key then it can only receive this when you transfer from the other machine (using Standard). You cannot have two licenses on one machine so would have to modify the serial key between Standard and Premium to control which version it can receive, This is done via the Control Panel > Programs and Features.