There are many GPT sites, which pay you for completing trial offers. These trial offers require credit card registration where you give your credit card details. You would need to cancel your trial offer before the free offer expires, or you would be charged full amount;  You can cancel it anytime after you are credited for this.  There are many online workers who want to complete trial offers, but either they do not have credit card or they don’t want to give their credit card details on these sites.  I personally think that we should avoid using our credit card for completing any offer on these online