Many people play around with their first key, generate bad user ids, add comments they later regret or simply forget their passphrase. To avoid such keys to stay valid forever it's usually a good idea to limit the lifetime to some 12 month. You can modify the lifetime of your secret keys later using the key properties window.
Se é a primeira vez que crea unha chave pública, normalmente é unha boa idea limitar o tempo de vida a uns doce meses. Pódese modificar o tempo de vida das chaves privadas máis tarde coa xanela de propiedades da chave.