Visit nannypay.com to purchase a new or renewal license. NannyPay2 licenses have a duration of 365 days beginning on the date you purchase the license.
Click on "Register NannyPay" under the Help Menu and you will be presented with a small dialog box. Copy and paste your user name and registration key (included in your Kagi invoice) into the appropriate place in the dialog box.
Lastly, click the "Register" button and NannyPay2 will be ready to use for the next 365 days. You can always view the status of your registration by selecting "About NannyPay2" under the "NannyPay2" (Mac) or the "Help" (Windows) menus