First it's not objectdock. For the price you are listing it's Object Desktop and it's $49.99 per year.

That entitles you to the included programs and updates for 1 year. If you renew the updates continue for another year and so on. The renewal price is much less and as of now it's $29.99

If you download from the Stardock store you receive the .exe files. As long as you save these along with the registration number to your computer you will always have them to use in the future.  

Keep in mind after the year is up you won't receive any updates to the programs if you didn't renew. If the OS or something else changes that requires the software to receive a major update or an update in general you wouldn't receive that. That is the only thing that could stop your programs from working.

Example: Say you had Windows 8 and used Start8. You decide to switch to Windows 10. Start8 will not work on Win 10 that is why Start 10 was made. If you are an Object Desktop subscriber you could just go the the SD store and download it. If you were no longer a subscriber you would have to purchase it as a stand alone or purchase Object Desktop.

Hope that helps.