Your Inklingo downloads never expire, so you can take as much time as you like to finish your quilts.
You get 365 days (previously 200 days) of "offline" access (when you are not "online") at a time. If you open one of the PDFs (shape collections or design books) and it has been longer than 365 days, you will be prompted to enter your email address and password again. That's all. This is designed to ensure that you know if there is a newer version. All Inklingo downloads have been updated to keep up with technology since 2008, and some have been expanded. It will undoubtedly happen again.
The 365 days is explained in the Download Instructions,
I think if you read the download instructions it will set your mind at ease.
You can force another 365 days any time. To do that, un-check the box at the bottom of the sign-in page (to open automatically next time) and close Adobe Reader. When you open again, you will be prompted to enter your email address and password and then you will be set for another 365 days offline.
To keep up with changes in technology, new versions of the downloads may be created. You will be notified when you log in if you should download a newer version.
This is the same whether the PDF is free or paid.