No, you should be able to use it forever. But if you buy under Object Desktop package and your subscription is over you can still use the software as is. What you can't have is any updates and installer from Stardock. So, as long as you keep your current installer, you can still install it and activate it using the same key.
Please refer to this https://forums.stardock.com/486310/object-desktop-support-faq#subscriptionlapse
Stardock Community Assistant.