Pricing: enable a combined 'free' allowance of devices+instance

[knolleary]

Our new pricing model for Team/Enterprise includes a minimum number of Instances of a particular type.

Currently, Devices are not included in this allocation - the goal is to include them so that, for example, the Team tier will include up to 5 Small Instances or Devices.

With our current model, Devices and Instances are handled as separate stripe items in the subscription. When a user adds/removes an instance or device, we update the corresponding quantity on their subscription of the appropriate item, taking into account the 'free' allocation.

The problem to solve is how to account for the free allocation to be spread between two different items in the subscription.

One option would be to no longer bill devices as a separate item at all; in the config, define what instance type a device should be treated as. The downside of this approach means the user no longer sees a separate 'devices' item in their bill and could cause confusion. Plus it makes it harder to pull stats from Stripe on usage of devices.

The alternative is we recalculate both device/instance billable amounts whenever a change is made to either. For example;

• team has 3 instances, 2 devices - currently all free as the combined total is 5
• they add a device - they get billed for 1 device
• they remove an instance - the device billed above is removed from the subscription as they are back under the free allocation

It could lead to fairly confusing invoices with all the adding/removing of items - but not sure it would be much worse than it is today given our usage-based billing.

I'm going to look at implementing this second approach as I believe having a separate device line item is clearer.