You will be able to make a purchase; however even if the commission is initially credited to your account, it will be deducted before you are paid. You will not receive any commission from your own purchases made through your own affiliate links. If you try to be sneaky about it and you are found out, then you may lose your account. The same goes for family members who use your links to purchase. While this is harder for Amazon to find out about, this is similarly against their terms and conditions, and you could be risking your account.