If you bought a physical copy, look for a sticker on the back of the DVD sleeve or inside the product box.

Are you installing Acrobat 2017 on a or a Mac computer? adobe acrobat pro 2017 enter license key

If you don't have internet, you may need an "Offline Activation" code from Adobe’s website. If you bought a physical copy, look for

If you purchased a physical copy, the 24-digit key is printed on a sticker inside the box or on the disc sleeve. If you bought a physical copy

If a trial screen pops up, click the "Activate Now" or "License This Software" button.