When you apply a token to your space, its value can be used to pay hosting invoices, which will be issued every 30 days.
Usage is priced by GB*month, in the same way electricity is priced by KW*hour. A 2GBm token lets you store 2GB data for a month, or 1GB data for two months. As a side note, 1GB gives you about 1 million text notes, more than enough for a productive life time.
The hosting expense is calculated based on your average storage usage during a 30-day period, rounding up to whole GB. For example, if your data takes more than 1GB but less than 2GB, then your expense will be 2GBm per month. If your data is less than 1GB, it will be counted as 1GB. Thus your minimum hosting expense per month is 1GBm.
Since tokens can be gifted from one user to another, it becomes impossible for us to track the real ownership of a space. And that is a good thing. The less we know, the happier we are.