Hello,
For Start11 there is not subscription base license, yet. Currently there are options to purchase Single or multi-device permanent license. And yes, permanent licenses should work forever as long as the OS is compatible with the product.
If you purchase Object Desktop, package, that also come with Start11v2 together with lots of other software. Object Desktop is subscription base license, and the products listed under it do stop working once the subscription lapse.
Thank you.
Basj,
Stardock Community Assistant.