If you want to keep thousands of photos and videos for free then the best application to store them is Google Photos. Google photos lets you export 500 images in one go so if you are having thousands of images then it may take a lot of time to download the photos.

However if you wish to download all the google photos, if you can export those using Google Takeout which is essentially used for exporting a backup of your google account and you can select from all the listed services offered by Google.