There is no storage cap! There is only "time remaining". You pay for storage in terms of "GB Months". So, for example, if you buy 1 GB Month and you upload 1 GB, your time will run out after a month. If you upload half a gig, your time will last for 2 months. If you upload 100MB (1/10 GB) then you time will last for 10 months. You can top up your storage at any time (or delete stuff to make it last longer!)