ObjectDesktop isn't an app. It is a collection of apps that is cheaper than getting each app separately.
If you have purchased a subscription to ObjectDesktop, go to the link below, sign in with the email you used to purchase, then click My Downloads, near top right.
All the apps that come with ObjectDesktop will be there (see reply 2), along with your serial number with which to activate.
I advise that you do not use ObjectDesktopManager, it has a tendency to bork the installs.
Anytime you need to access your apps, here is where you'll find them.
I would also advise that you keep the downloaded app installers archived. This way, if anything gets retired, which does sometimes happen, you'll always have what you bought. In case you need to reinstall them.
The ObjectDesktop serial will be the only key you need. Use it with each app as it asks for it on install.
There will be no money taken from you without consent. If you choose to renew in a year, you control that. Your apps will still work if you don't renew, you just won't get the updates and other perks that come with a subscription. The subscription is a deal where you pay for a years worth of updates, you'll get early access to betas, etc.