The model used by many app developers, whether they work for a major studio or a reduced team of people, is usually the freemium model. In other words, they offer their products for free and then if users want to access certain extra functions, they charge them by means of in-app purchases.
Download paid applications for free: a dream come true
But if you think that it isn't fair and that you deserve to download applications for free because it's your God-given right, you can try out Panda Helper. It's an Android app store where you can find paid apps for free and game MODs that offer us functions and items totally free of charge without having to pay a cent.
Here you can find thousands of patched applications to access premium functions with paying a cent: antiviruses, apps to listen to music, video games... everything perfectly organized and classified so that you can easily find what you're looking for and with suggestions, just in case you just want to follow the trend.
Download this APK right now and give those damn developers that want to get paid for their work a hiding. But remember, it could be your job we're talking about tomorrow.