If you send those tokens you bought to an unregistered Ethereum address, yes you would. However, if you send those tokens to a registered address, you would not. The key is stored in the contract, so as long as the Ethereum address contains tokens and is registered with a valid key, you can move tokens into or out of that address as often as you wish. What matters most is that during the mainnet snapshot, your tokens live at the registered address. But until then it's mostly irrelevant.