You have excellent taste in gifts! WineRatings+ is free to download, and requires a monthly subscription to access its 400,000+ expert tasting notes, lightning-fast search, customizable wine lists, and more. This type of subscription is known as an "in-app purchase" for both Apple and Android users, and renews automatically every 30 days, at $2.99 per month, unless the renewal is cancelled.
At this time, Apple and Google do not support the ability to gift an in-app purchase, such as the monthly subscription to WineRatings+. However, you can gift an App Store (Apple) gift card or a Google Play (Android) gift card, either of which can be used toward in-app purchases, along with a note about why your gift recipient is going to love WineRatings+!
(Depending on your state of purchase, sales tax might be deducted from the gift balance every month — meaning a $36 gift card might not cover a year of subscription renewals — so consider taking that into account on your recipient's behalf.)