Can I set a monthly cap per property?

Yes! You can set an overall monthly cap, then divide that cap between properties.

1
Click on the "Billing Information" link under "Account" on the left side of the screen.

2
Next to the corresponding card you want to change, click "Edit this card".

3
Go to the "Edit Your Monthly Cap" section towards the bottom.

 

Under "Per Property Cap Type", you can set a flat cap that will apply to each Plus! property, or you can set individual custom caps for each property.