Purchasing credits for Picture gallery space

Alright do you just get 100, 300, 500 mb or w/e you paid for, for each moth or do you just get 500 mb.

it sasy this under the credits store. "While adding extra storage, you will have a one-month validity. You can add extra time after"

or do you just get that space for one month.

Thanks,
Cody

I haven't bought any gallery space as I never did use it.

But if you buy gallyer space it will be for one month unless you add more time.