Help understanding credits

When I buy credits to add more storage or my own domain, is that a monthly thing or just one time thing ?

1) 1600 for the domain, one time purchase ?
2) 500 for 500MB storage monthly or one time ? (I think its monthly, but just dbl checking)
If, what happen if I run out of credits, do I losse all the pix on storage or just can't add anymore
till I buy more ?

thx!

Hi,

1) It's a 1 off yearly purchase.
2) it's a month by month process. If you don't purchase it by the start of the new month you lose the images and have to start again.