How can I get my Subscription ID(s)?
To get the numeric IDs of your Software Center subscriptions (purchases), go to this site:
From there, hover your mouse cursor over the title of the software you want to get the ID for. Right-click, then select "Copy link location". Then paste the link into whatever program you want to store the ID in, such as your email program when asking for support.
The subscription ID is the numeric part of the link. For example:
The ID is the last portion, 123456.
This number can help us uniquely identify your purchase and look up the details.