The entire EXLskills economy – and all products/services offered on EXLskills – are priced in "EXLskills Coins." Each EXLskills Coin is purchased for exactly US$1, at the time of writing. There is no secondary market for your Coins and they are to be used solely on EXLskills – similar to how you would use airline miles or points.
In order to purchase EXLskills Coins today, you must have a valid credit card that you may add through the billing dialog here. When you add your credit card, you may see a pre-authorization for US$1, however, it will never be charged unless you explicitly purchase coins and/or other services on EXLskills. Prior to any charge, the system will always inform you, and unless previously authorized, get your consent.
If at some point you wish to have your credit card 'forgotten', you may do that in the same billing dialog that you used to add your credit card. Once your card is forgotten, your coins will remain active indefinitely and you may continue to use EXLskills premium services – however you would need to add a credit card again if you wish to purchase more coins.
If you have any concerns or questions regarding your Coins, bill, or premium services on EXLskills, please contact support via the chat option in the bottom right corner of all EXLskills. You may also be able to find an answer instantly in our help center.