Description
E.g. if there are now 4 more students enrolled in the course, the administrator may prefer to edit the course license and pay separately, even if there are funds on the account, because those funds are ear-marked for other purposes.
Having a detailed description on the receipt that "this is for license edit from this_state to that_state" is a huge bonus.
An easiest and quite flexible way to implement it may be supporting a "license edit" product in the cart, so that it is treated the same way as everything else for checkout purposes.
Potential issue - when a live license is edited, the price is calculated "from now" and if several license edits are loaded into card, there may be a bit of a delay from staging the edit to actually executing it, with effective date in the past. I think that having that date in the past by 1 hour and collecting/accepting the charge for it is perfectly reasonable. If it is more than that, maybe some actions may be taken.
A possible approach - make license edit items in the cart live: recompute their start date and price when the cart is actually shown. Then if somebody is editing a bunch of licenses before paying the price may drop a little (it cannot go up). I would NOT change the amount from what is shown to the user to what is sent to Stripe, however, that's just confusing.