active pay as you go purchases may interfere with license purchases in the store

[williamstein]

Right now when you make a license purchase in the store, first you top up your balance so you have enough to cover the purchase, then you make the purchase. However, these steps can take a few minutes, and if you have an active pay as you go purchase, then your credit will suddenly not be quite enough to cover the purchase!

See #7065 (comment)

Three distinct ways to address this:

• take into account the current pay as you go rate, and add 30 minutes of that to the amount that you have to add to the balance when making the purchase, or
• allow the balance to go "slightly" below the min allowed amount.

(@schrodingersket identified this issue)

[williamstein]

We will clearly have to change things so that when you make a store purchase, it includes the metadata for exactly what is being purchased. That eliminates this issue...

[williamstein]

Addressed in #7979

Also, payg is not continuous! The charges happen maybe once per day in discrete jumps, and it is highly unlikely to happen in the 5 seconds during a purchase.