Thanks for reminding me / us about this, it’s an important point.
Keep in mind that this plugin:
Uses a widely used ruby gem, which supports its use(s) of Nominatim.
You can control the geocoding rate limit using the setting
location geocoding rate limit. I just added another setting that lets you control the search debounce on the client:
location geocoding debounce
Has 2 different types of search. One could be described as “Auto-complete” (depending on the other settings you’re using). The other - “input fields” alongside a “Find Address” button - is definitely not Auto-complete.
I am currently using nominatim in developing and staging environments with the second type of search - input fields with a button - in various ways (e.g. in a Custom Wizard form).
But yes, you shouldn’t be using Nominatim (with either type of search) for medium or heavy production use, which is what their policy is concerned with. You can see what they have in mind with “Auto-complete” by their top line usage requirement:
No heavy uses (an absolute maximum of 1 request per second).
Generally speaking, as mentioned in the OP, particularly if you are using this in production, it is important that you review the T&Cs of any geocoding service you’re using and assess them according to your own circumstances. Complying with the T&Cs of a service you’re using is your responsibility.
Could you give me some more details? What zoom setting are you using? Which map is it (mini-map or topic list map)?
Have you tried OpenCageData? They seem to do basically what you’re suggesting and are already supported by this plugin.