If you cannot find the paper copy, you can retrieve it digitally if the software was previously registered: Adobe Account: Sign in to the Adobe Accounts page and look under Plans and Products Registered Products Order History: If purchased directly from Adobe, the key is listed in your order confirmation email Installed Software:
The direct successor to CS5.5, available via a monthly subscription.
If you miss the visual editing of Dreamweaver, Pinegrow is the best modern alternative. It works with WordPress, Bootstrap, and Tailwind. It is a perpetual license—just like CS5.5 used to be.
Unlike modern Creative Cloud software, which uses subscription-based sign-in, CS5.5 relied on two things: