Ok, thanks to your answer(s) now the strategy is very clear: it's better to upgrade after one have one or more referrals. Only for daily checklist (mainly), 17$/year seems too much for me. The difference w.r.t. standard it's about 9% or so, which helps you to compensate the premium fee during a year if you're producing something like 50c/day,
every day . For making that you need to have and to make at least a survey,
every day, if I have a good view on the business. Of course, if you have referrals, the situation is changed. Obviously, you can think that there are days when you're doing more than 50c, but there are a lot of days when you're doing almost nothing, right ?
Thank you again, to all of you.