If you think that once you have got a customer to buy from you once, they are suddenly going to continue doing business with you, think again.
The mistake many businesses make is that they assume once a customer experiences your product or service once, the decision to switch suppliers for ever is already made.
The truth is, that unless you ask the question, you simply do not know why the new customer decided to buy from you on this particular occasion and you certainly do not know if they are going to come back.