Your progress is saved even if you change computers.
If you purchased the standalone version in the past, you can exchange your serial number for a free Steam key to add the game to your Steam library. Why "Free Keys" Should Be Avoided city car driving 159 activation key free top
Some retailers still sell boxed copies of CCD 1.5.9. These contain a printed activation key. Check eBay or local second‑hand game stores – but beware of used keys (they may already be activated). Only buy sealed copies. Your progress is saved even if you change computers