All license delete

Hallo,
i've got a problem.
I installed Spybot with license to a portable PC but after i uninstall it.
I install spybot to my pc with the same license and i had problems so i uninstall it and reinstall.
A message appears, it say that i've just two "activation" and i'm wrong in license terms.
Is it possible remove older and use only the last? i coul'd reset all and reinstall spybot on my pc.
I'm testing spybot to buy other license for other pc.

Thank you