Commerce Stripe webhook
It sounds like you want to load the user object from the email address, set some field values, and save it again.

In code that would look something like this:

if ( ($account = user_load_by_mail($customer_email) ) {
  $account-&gt;field_foo[LANGUAGE_NONE][0]['value'] = $event_json-&gt;foo;
  $account-&gt;field_bar[LANGUAGE_NONE][0]['value'] = $event_json-&gt;bar;

  user_save($account);
}