Today Adobe only rents its professional "Creative Cloud" stuff. You install the programs normally, but they die as soon as you do not pay the rent. The software needs regular "payments ok" acknowledgements via the internet or they do not run.
There are several different licensing schemes available, but perpetual (pay once) isn't one of them.
In theory you can find in Ebay or other marketplaces Adobe pro software packages from the era before Creative Cloud. They have some drawbacks:
- you cannot be sure are the given keys valid
- you can get a crack with a bunch of malware
- if someone sells his used old packages, the purchase must be accepted by Adobe. Otherwise the right to use doesn't get transferred.
- the prices are higher than they were when the packages were new
- nobody quarantees the compatibility with newest Win or MacOS.
Thus I cannot recommend Ebay purchases. I have bought my ancient package "face to face" and all went smoothly.
If you can't afford Adobe pro stuff for hobby purposes, goto freeware or take something less pricey commercial software. Search for alternatives. PS, Illustrator and InD seem to have them at least to some degree. I do not know Flash well enough. Check this: http://www.animationinsider.com/2015/01/software-vectorian-giotto-an-actual-flash-alternative/