AXSpace limits the number of registration per 2 hours. If you consider the credit banner in www.axspace.com website you will see two boxes :
1- "Credits left": indicate the number of available registration in current period.
2- "Time left": the time left for "Credits left" to be reset to maximum.
So if you get this message "There aren't enough Credits available at this time", you should be patient for seconds which are shown in "Time left", after "Time left" countdown finished, "Credits left" value will reset and you will be allowed to register new account.