As a former software developer who knows all about piracy and the real costs it inflicts on the industry (tiny in reality, pirated copies != lost sales, you can't assume that every pirate would buy a copy of your program if they had to), I can say one thing... Use your dad's version of Photoshop at first, then buy your own license later if you decide to pursue this.
1. Software activation is a Windows only thing. The Mac version doesn't require it (mine didn't). Honestly, the whole activation thing is a bad idea and I wouldn't be surprised if Adobe drops it altogether since it doesn't prevent piracy at all and it greatly inconveniences legitimate users.
2. It sounds like you're still kind of starting out. You might not even know for sure yet if this whole "making pictures for a living" thing is really for you. Don't drop $500-600 on something that could end up collecting dust.
I've changed careers once already, and before I chose the first career, I must've changed my mind about my life a dozen or more times. It happens.
I'm going to be dead honest with people right now. I used Photoshop for a couple years before I bought my own copy. It's important to note that I did, in fact, buy my own copy (and I buy all of my graphics software nowadays), but I was not going to do that before I actually knew I was going to need it. If Photoshop only cost a hundred bucks (or heck, even a couple of hundred), I'd say buy it. But the price of this stuff is truly prohibitive for somebody just starting out, for somebody who is still exploring all of their possibilities and for somebody who doesn't have all of their equipment and supplies yet.
You shouldn't have to go into debt just to start tinkering with the tools of the trade, and the developers of this software shouldn't demand that of you, it's unethical to expect every potential illustrator and designer to pony up thousands of dollars just to get started, but people seem to accept it as the way of the world anyway. If paintbrushes cost as much as Photoshop does, there'd be no Picasso, Monet or Van Gogh.
I don't approve of software piracy in general, and I do wholeheartedly believe that once someone starts to take their work seriously, they need to invest in the tools of their trade. But when you're just starting out, get what you can however you can. Buy, borrow or copy. Once you've learned the skills of the trade and you feel comfortable making the decision to do this for the rest of your life, then you start buying things, and then you start feeling bad about the things you haven't bought yet.
Software developers already understand this to a certain extent. Academic pricing is a conceit to this reality, but Adobe's academic prices are still way out of whack. They used to be lower, but then Adobe's marketing division realized they could make more money selling large scale licenses to universities than they could selling academic copies to students (and profit was never the point of selling academic copies, it was about building brand loyalty and ensuring that there was a community of professional users available to market to -- ie, they didn't all drop out of design school for lack of funds). Now that Adobe has conquered the graphics software market, brand loyalty is a moot point. In order to maximize the profit potential of university licenses, Adobe had to accomplish two goals.
1. Encourage students to use university computers rather than their own, which in turn encourages universities to increase their facility spending.
2. Make as much money off of each university licensed copy as possible.
Raising the academic price of Photoshop from $100 (which is about what it was when I was in college the first time around) to $250 (which is about what it is now) accomplishes both of those goals.
Adobe's hard working programmers aren't going to get laid off and their kids aren't going to starve if every new designer and student uses a pirated copy of Photoshop for a year or so before buying their own legal copy. They make most of their money on typefaces anyway.
Honestly, I think piracy of Adobe software would plummet if they acknowledged this reality and gave us a legal means of using Photoshop for a while, like a temporary lease. Pay us a hundred bucks now and you can use a full version of the latest Photoshop release for a full year. Pay us the rest of the amount at the end of the year and we'll give you any updated vesions if they were released and remove the timer from your software. Don't pay us and your software deletes itself (or whatever).
Sure the system could be hacked to give someone a hundred dollar version of Photoshop, but someone who does that would hack the full version anyway without paying anything at all. At least this would get some revenue from the tens of thousands of "honest" users who don't want to pirate Photoshop but feel they have to. Most software pirates aren't dishonest people. They're just people trying to get something done with limited resources. The industry's current attempts to demonize piracy just end up alienating them from a huge population of their existing user base, a group of people they should be trying to find ways to make money off of rather than trying to put them all in jail.
If you can't change the world (and in this case, they can't), you should try to make the best of it, however it is. The first software company that figures this out and puts this philosophy into action is going to bury their competition.
In the immortal words of Socrates, who said, "I drank what?"