I have a 100 GB, £1.59/month type of Google Drive account that's attached to a domain name I want to terminate. I'd like to transfer the files stored there to one of my free Google Drive account.
Is it possible, and if so, how?
You can use Google Takeout to transfer the complete archive of your data to another account.
To move files without downloading and re-uploading :
From your question, it sounds like you have the Basic G Suite service (see https://gsuite.google.co.uk/pricing.html for the pricing plans). One suggestion to solve your problem is to temporarily upgrade to Business G Suite, so that you can create a Shared Drive, then follow these steps:
For other readers, if you don't have access to a Shared Drive, my top suggestion is to contact Google Drive support for help (this requires a subscription to Google One), to ask if they can do it.
The main issue is transferring ownership of your files to the new account. If that doesn't happen, the files will still be stored in the old account, and one could accidentally permanently delete them if one isn't aware of that. Simply sharing all your files (which can be done by first pressing Ctrl + A) will not change the ownership, and it is impractical to individually change the ownership on every file. Changing the ownership of a folder doesn't change the ownership of the files inside it.
One (imperfect) way to migrate an account is to:
Although the ownership of all offline files will migrate, the reason why this is imperfect is that the ownership of Google Docs will not change. You would need to look through all the files that the new account doesn't own (by searching
-owner:me at the top of the Google Drive website (note the minus sign)), then change the ownership of your Google Docs from the sending account. This may be feasible if you only have a few Google Docs.