login and payoff are nouns. But can they be used as verbs?

I know that words like login and payoff are properly nouns but I increasingly notice many (not at all uneducated) people use them as verbs:

Will you payoff your credit card this month?

and

Please check this when you login.

To me (a non-native English user), that seems incorrect because separating the core noun from a preposition is what I was taught: Please check this when you log in. (My emphasis)

Is this use proper or not?

Solution 1:

I agree with you. (I am a native English speaker.) It is more correct to say "log in" or "pay off" when using these words as verbs. However, usage will dictate whether these eventually become solid words, even when used as verbs. Until that time, however, it is better to not spell them solid when used as verbs.

Solution 2:

Pay off and log in are phrasal verbs. The first is always transitive and, as such, allows the particle off to be moved. We can say ‘Will you pay off your credit card this month?’ but we can also say ‘Will you pay your credit card off this month?’

When log in is used intransitively, the particle in immediately follows the verb log, but, when it is used transitively, the particle can also move. We can say both ‘I’ll log in John now’ and ‘I’ll log John in now.’ However, when the direct object is a pronoun, it immediately follows the verb. We’d say ‘I’ll log him in now’, and not *’I’ll log in him now.’

These are compelling reasons for verbs such as these to be written as separate words.

Solution 3:

To add to what Barrie England has said, as long as the past of these phrases is logged in and paid off, it is unhelpful and confusing to regard them as single words.

If it happens that people start saying I loginned or they payoffed, then they will have become single words, at least for those speakers.

Solution 4:

I speak native UK English and have worked in IT for many years. I certainly see "login" and "logon" very, very frequently used as verbs in user guides, manuals, websites etc. In fact I'd say it's the standard usage. I'd regard "log in" as verging on the antiquated in IT.

If I saw "Will you payoff your credit card this month?" I would automatically assume the space had been missed accidentally.

eta : Look at the OED website which uses "Log in" and "login with" - interesting. In fact they have "Log In" as verb, then "Subscriber login" which could be either, then at the bottom two "Login with"s which may or may not be set by the OED itself.