Why not just pay the $19.99 whenever a major release is out instead of $199.99? Then basically all new extensions or major version upgrades would only cost $19.99 each (cheaper if more than one extension in the same month).
So if I had paid for a monthly subscription the Sculptor3 upgrade would only be $19.99 instead of the ridiculous $49.99? The hypothetically if a new version of DataAssist came out in two months I could pay another $19.99 and get that version too?
So wouldn't it make more sense to just pay the monthly when ever there is an upgrade or product you want instead of paying for the months that there are no upgrades or new products?
But your ability to use the extension would ONLY be for that month... the subscription plan is a lease - you only can use the extensions WHILE your subscription is current... so no, you wouldn't be doing better that way. If you buy the extension, you own it and can use that licensed version forever. If you lease, you can use while your lease (subscription) is current and paid.