LastPass shows how to do two-step verification wrong

I finally signed up for LastPass Premium after years of using the free version of that password-management service. And I’m starting to regret that expense even though $2 a month should amount to a rounding error.

Instead of that minimal outlay, I’m irked by LastPass’s implementation of the feature I had in mind when typing in credit-card digits: support for Yubikey U2F security keysas a form of…