To increase a customer's price you will need to edit their subscription.

The new price may already be in Stora as an option, but if not, you can create a unique price against the unit type (50 sq ft etc). More information on how to do this can be found here.

When you have created your new price point navigate to your customer's subscription. Select the Edit Unit Types option as below.

You can then select the new price and you will be able to select the when to start the change, as immediately, on next renewal or backdate. (Recommended option is 'on next renewal' as you will likely have given the customer notice of the increase)

Select 'Preview Changes' to review and then 'Change units' to confirm the change.