Hello,
No, if you purchase Start11 v1 now from Steam, you will need to purchase again when Start11 v2 is available on Steam, but, from what I understand, it might be with some discount. I believe, if you must purchase it via Steam, it is best just to wait for Start11 v2to be available on Steam. It should be available on Steam soon.
Thank you.
Basj,
Stardock Community Assistant.