During the setup process for a GCP account, I saw that free credit of up to $300 can be spent over 90 days, instead of over 1 year. This seems to have changed since the course was published. https://cloud.google.com/free/docs/gcp-free-tier
Confirmed as well. I created my account end of 2020 and it was already 90 days with 300$ credit.
It is sad when companies impose restrictions on such things, because always something good and convenient goes into oblivion. Although if you know where to go, the situation can only improve. For example, I found a cool service FitMyMoney, where I found information on the most favorable offers, and in general, how it all works. This thing is really cool and saved me a lot of money and nerves. I advise to try it!