Question:

How many keywords can you place per page ? I understood that you can put in as many as possible but will they rank? My developer says they can only put 800 per page but it is a waste of time. I am a little confused as others say there should only be a few. Can you help me please ?

Answer:

Google does not really use the meta keywords tag as a strong ranking signal at all. However, on the flip-side, if you have anything more than 3 to 5 keywords for any one particular page then you are treading dangerously towards being penalised for keyword stuffing.
Our advise is to avoid adding any keywords tags on a page unless there is a typical misspelling or common typos – or synonyms – that your customers typically search for. For example: Email versus E-Mail; Web Site versus Website; horse-riding versus horseriding). But anything more that that is dangerous and pretty much useless to your rankings. So to answer your comment of 800 keywords on a page, that is most definitely going to get you penalised for black hat keyword stuffing.

picture showing black hat SEO