Is this application a one-time payment or monthly?
Hi,
gpg4win is completely free, no payment is required at all.
Can it be used for commercial purposes?
since it is free software, you may use for whatever purpose you like.
however, if for your business you need direct, professional support as well, you should consider licensing GnuPG Desktop instead.
Is GnuPG Desktop paid ?
professional support is not cost free. if you follow the link above, see the pricing information at the end.