This is from the Google email i got
How to keep your account active?
The simplest way to keep a Google Account active is to sign in to the account at least once every two years. If you have signed in to your Google Account recently in the past two years, your account is considered active and will not be deleted.
Other ways to keep your account active include:
- Reading or sending an email
- Using Google Drive
- Watching a YouTube video
- Sharing a photo
- Downloading an app
- Using Google Search
- Using Sign in with Google to sign in to a third-party app or service
There are some exceptions to this policy. Examples include: a Google Account with YouTube channels, videos or comments; an account that has a gift card with a monetary balance; or an account that has a published application, for example, one that hosts an app on the Google Play store. Other exceptions to this policy are available here.
login to youtube from a browser with that account and watch one or two videos and sign out. do this every 8-10 months to keep the account active.