Welcome to the community! Seems like you are planning to use the Non Humanitarian Server (HHI Server). In this case you are able to store your data up to 5 GB. Please note, its not per month. It’s in total i.e. it should not exceed 5 GB.
As a way-out you could download your collected data (and empty your account’s storage size) once it is about the touch the threshold.
If you exceed the 5 GB storage limit, you will not be immediately cut off from uploading more data. There is no set grace period, but you’re likely to be contacted by someone at KoBo and be asked to free up space to return below the limit or else face a freeze on your account. If you wish to go over and keep the data that exceeds 5GB of space, please email firstname.lastname@example.org to ask about payment options.
For further details, please feel free to have a look at the support article here.
Have a great day!