Hi If you are a genuine vendor and honest then you would provide the following:
A back test up to and including 2012 preferably at 99% modeling quality
A real money live linked account there on myfxbook.
If you just SAY that your EA is great and has no losses and makes millions based on a couple of back tests then it is hard for people to take your product seriously. Anyone is capable of making wild claims without proof. Unfortunately in this industry such dishonest claims are the norm, every year there are many EAs which say they are brilliant yet when put to the test are rubbish.
It is up to you to prove that this EA is different, and that you are an honest vendor. There is no reason not too, unless of course you can´t, as providing REAL proof will generate many more sales.