So start paying up your debts. Did you say you don't have any? that's a lie: you owe yourself some (a lot) working hours for programming, distributing, promoting the app.
Also, you had to buy a mac which is also an expense, an iphone or ipod touch, etc...
Step one: sum all that money. Put it wherever you like and feel free to spend it: It's your delayed salary.
The next step is trying to figure out how much money you need to "forget" about getting money everyday.
Maybe 10k/month or 20k/month to cover all your living expenses and get all (physical) things you want without having to worry about money. Let's suppose you're happy with $20k/month (tax free, of course).
Step 2: How much money do you need to have to get $20k in interest ? Figure out that sum. Remember that next year today's $20k will be something like $19,002 or something like that.
First: Keep making money (selling your app, and building one or two more).
Second: Invest in something like bonds (us, corporate bonds, etc...) with good credit rating. You may earn between 1.5% - 8% yearly (if you can buy bonds at discount, better).
Third: Invest in stock, funds, etc... just follow the tide: don't try to outsmart the market because you will fail.
Fourth: When you have time, start looking at derivates. Then, build your own guaranteed-credit deposit with options and swaps. Beat next year inflation (mostly on autopilot).
Five: Enjoy !