Can I use upx packer to compress a commercial program?
Yes, you can. Please have a look at the UPX license. There’s a special exception for commercial applications so they can use UPX. Note to Zifre: UPX is GPL, but it’s not the same as creating an image with GIMP, since part of the UPX code is added to the commercial application (the decompressing part). That’s why the exception in the license is required.
