OK. I'll Be blunt. I've activated my install MANY TIMES. Period. If you don't believe me, then sorry. Its more than possible to activate an install more than once. You can reinstall the game on your PC as much as you want, at least in the beta. You obviously don't have a beta key to test this yourself. When you install the game, the keys are stored in the registry, and the game is activated when you go online. All you have to do, is wipe your computer, or just revert to a previous system restore date and install again and it makes you activate again. I've said this several times on the forums here.
EDIT: I also successfully have a registry change log and filesystem change log if anyone wants to see it, PM me. Its actually got some very interesting information in it(cryptographically).
EDIT2: I can also confirm that 3pc's is the max machines usable for the Key, however you can reinstall and reactivate on the same 3 pc's as much as you want, contrary to the rules set by securom with bioshock. There is NO activation limit, Unless you install on more than 3 nodes.