Theoretically yes, once the AirTag is deployed the keys should be static and you should be ready to go. Apple should also not be able to "ban" the tag at some later point in time.

I would suggest signing into a separate Apple account that's under your control to pair the AirTag, however. Not due to the risk of being banned, but because I have the suspicion that removing an AirTag from your (friend's) account may prompt the device to instruct the AirTag to reset. But if you sign into another account, pair it using an iDevice and then log out, that shouldn't be an issue.