Is it possible to acquire a LOR without having a face to face meet up/agreement?

Of course it is not a good idea, preferably one would meet up with the professor to make the agreement.

In my case, I've talked to the prof for a year, and then went off work for a year, now I need a recommendation letter. In September I emailed him my situation WITH the invitation for a meet up at his office. He told me he is willing to provide a reference, but did not address the meeting up issue.

Now it is close to application deadline and I've yet to received the letter from him despite a few follow ups. I'm worried it is the reason is that I did not meet up with him so he might have forgotten who I was (which is understandable). I will attempt to email him once more with a more urgent tone, perhaps he will respond this time, but should I also invite him again to a meet up or is it too late?

Any profs care to share their ideas?