I've mentioned this over at DAZ, I'm going to mention it one time here then get on to other things. The problem is this: DRM does not generate sales for entertainment digital items. Those people who aren't paying for the right to use your stuff are never going to pay for the right to use your stuff - they just will not use it if you make it impossible. Shady businesses that use your product in money making enterprises will pay for it if they have to.

The problem with DRM is that it makes your product more difficult to use for your paying customers, plus it is costly to maintain and develop.

So if you are adding DRM to your product, and it is used chiefly for entertainment, you are going to get lower sales at higher cost. It will not raise your sales. Which is exactly what the music, book, and movie industries found out. Movies still do it to stop people from selling their product illegally, that you have to stop or you go out of business.

If you are incised that people are using your work without paying you, and your bottom line is you want to stop them regardless of lost sales or costs, then go for it, use the hell out of DRM.

If you are trying to increase your sales, you better try something else.