sorry for double post but here is what probally happend.
after i switched to my new internet of course my ip ( i think) changed for internet since it uses the ip for my old internet it thinks i am a person that's trying to steal my own id so it locks me out .
If I am correct, this only happens when two people at the same time (Different IP's) tries to use the same ID, or the distance is over a certain amount (Probably about 600 miles or so).
Cause I usually go to my grandparent's house alot (Meaning my IP would be different, since its a different connection), and take my laptop there to play Blockland, and I've never got revoked because of that, and I also went to visit my dad's side of my family a couple states across, and played Blockland there.
If anything, your probably typing in the key wrong, make sure you are by looking at each letter and comparing it to your email with your key.
If not, do what Pandan suggested.
If any of these prior suggestions fail, I would email support@blockland.us