Google Play doesn't let you gift a subscription, but you can send money or a gift card that the recipient can use to subscribe.
Send Google Pay money via Gmail
When you send Google Pay Money, the recipient can use it to pay for items from the Google Play Store. To do it, follow these steps on your phone:
Open the Gmail app.
Draft an email to the Google account email address they use on their phone.
Tap the attach button and select Send money. Enter your payment info when prompted if you haven’t already done so.
Enter the amount of money the subscription costs.
Add a memo if you’d like and tap Done.
Send the email.
Once the recipient receives your gift, they can use it to subscribe to Pro.
Buy a Google Play gift card
You can decide whether you want to buy a physical card or a digital one, and they come in a range of amounts. To send a gift card online, follow these steps:
Go to the Google Play gift code page on Amazon.
Choose the design of the card.
Choose the amount of credit you want the card to hold.
Enter the recipient’s email address and all the additional information that’s required. You can also choose whether you want the card to be delivered right away or at some other time.
Tap Buy now.
Once the recipient receives your gift, they can use it to subscribe to Pro.