While I would think most subscribers to Findmypast take out a 1, 6 or 12 month subscription, there has always been an option to purchase credits instead, however it seems that are now being discontinued and are being replaced by a Pay-As-You-Go option instead.
The following is an announcement that came in to my inbox from Findmypast:
We wanted to let you know that we are in the process of discontinuing Credits and introducing a new PayAsYouGo process called Micropayments. If you have active Credits, it is important you are aware of these changes.
All Terms and Conditions related to Micropayments can be found in Section 5a. of the Terms and Conditions here.
As of Wednesday, 14 July 2021, we will also be making a change to the way Credits expire. Credits will no longer be extended or reactivated when you purchase a Subscription or additional Credits. All Credits will expire 90 days from their point of purchase.
If you are not sure when your Credits will expire, please log in to Findmypast, go to ‘My Account’ and then ‘My subscription’ where the expiry date of your Credits will be displayed. We would like to take this opportunity to encourage you, and your audience, to make use of current Credits before their expiry date.
So if you do use Findmypast credits at present, take note, and be aware that they are being phased out.