I used to own the Adobe suite a few years ago. After talking to the Customer Support, it is the CS5.5 version. Is there a link where I can upgrade that version to CS 2017?
To upgrade and subscribe to the latest versions, you sign in to your Adobe Creative Cloud account, typically Creative Cloud pricing and membership plans | Adobe Creative Cloud
You get Photoshop CC2015/17 plus Lightroom for only £8.57 a month (UK).
There's no upgrade path from a creative suite to the creative cloud. It's a whole new licensing model, and the suite concept is history.
For a while, suite owners got reduced subscription price for a year, but I'm not sure if that still applies. In any case, if you just want Photoshop (and Lightroom) - Derek pointed out what a good deal this is.
Note, just so you don't misunderstand, that "cloud" is just a marketing name. The only "cloudy" thing is the licensing - the application is still installed and run locally on your own machine.