Do images in 'user-images.githubusercontent.com' have expire time?

I'm servicing a blog using GitHub Pages.

The blog service has many images files to upload, so I needed a repository that stores images.

While searching for a repository, I found a method using github-issues.

I capture my image first and then paste to github-issues body. It will be changed to a markdown image tag that has an image url like:

![image](https://user-images.githubusercontent.com/{path}/{filename})

My question is: does the image stored in githubusercontent.com have an expire time?

If the image has an expire time, it will not appear on my blog later.