Z:gnu-www-ja-rms-why-gplv3--5a6295-GPLv3 ensures you are free to/en

GPLv3 ensures you are free to remove the handcuffs. It doesn't forbid DRM, or any kind of feature. It places no limits on the substantive functionality you can add to a program, or remove from it. Rather, it makes sure that you are just as free to remove nasty features as the distributor of your copy was to add them. Tivoization is the way they deny you that freedom; to protect your freedom, GPLv3 forbids tivoization.