Ah I can understand why that change wouldn't be an option then, thanks a lot for the clarifying response.
A problem though is I wouldn't have had as much concern if the single month personal license was the price to pay. In Australia, even as an individual you require a 'business' for any earnings (my games are via my business/logo etc even when free for those that may not be), so I required the business annual license. When I was originally looking to what license I required I'm pretty sure that was the case in another country too.
This limits my option to every second year paying for an annual business license for ideally a single build of a free game.
This is certainly not a common situation, but if others encounter this too, in the future if it were possible at all for a monthly based maintenance license-allowing opening and building of a project, for projects without any monetization, at personal license pricing, that would be greatly appreciated.
Though I can absolutely understand why that might not be an option either as I don't know the extent of the behind the scenes work you'd need to set that up.
At least it's available still on the web so if discovery of it grows/interest of it on mobile is desired more I can consider purchasing the license again at that time.