I lost mine. Or rather one of my children decided to hide it in the fireplace.

I didn't play for three weeks while it was lost, because once you de-register it, you can't then re-register it back on to your account. However, after three weeks, i needed my fix. I raised a ticket with S-E and they took it off my account within an hour. Fortunately, i had a second one (FFXIV CE), so I could register that straight away to keep my account secure, but otherwise, if you wanted the security I guess you'd have to buy another.

Of course, fast forward two weeks and the weather's getting cold. As I'm preparing the fireplace for the first time that year, I notice my old security token in the fire grate. I still have that and it still functions, but as far as I've been told, I can't ever register it to another S-E account.