For the Tablet install, you will be installing Norton Mobile Security, NMS, from the Google Play Store. Log into your Norton Account at https://manage.norton.com and click on Services tab, and find your current Norton Security Premium subscription. Click on the Download button and follow the directions to install on another device. Send the email to your wife's email that she can open on the tablet. Follow the directions in the email to install on the tablet.
As noted, this gets installed under your Norton Account. You may have to sign into your account from the NMS app to activate the full features.
She can activate it with your key but the product will be under your Norton account, there is no way to change that since the key was first activated to your Norton account.
She can however use "her" identity safe vault because the Norton account used for the key does not have to be the same account used for identity safe.
Go to Help on the top right of your NS Premium. On the right side you will see Add a Device and follow the instructions from there. Please have her run Live Update and restart as necessary. The latest version is 22.8.1.14
Another way you can do it is to have her use this link
www.norton.com/latestnsbu For Activation she can enter you key and your Norton Account. Please run Live Update until there are no more updates. Please restart as necessary. Her year will start when yours started.