A spoofer doesn't change your HWID permamently, unless previously stated on HyperCheat's website. Every other spoofer I've worked with, cheat or not has worked this way. That was my understanding, as that is how it is for everything else I've used.
As well, the cheapest cheat is still base $8 USD, which isn't entirely worth it imo if you aren't going to use the cheat. If you could let me know where you found that the spoofer is permanent that would be great.
EDIT: I think the lapse of understanding here is that you are talking about if you keep your subscription. What Goku is asking is if he can buy the cheat for a single day and it would change his HWID after his subscription ran out. No other HWID spoofer I've seen implemented in cheats has done this, and from everything I've found here so far, this is not how it works. (Buy cheat = use spoofer - cheat sub runs out = no more spoofer).