Keep imovies I make on my Device - Iphone

Add the movie to your Photos library

After you’ve saved the movie as a file, you can add the movie to your Photos library, store it in iCloud Drive or save it in another location. If you want to email the movie using another email client or by using another service, you should also save the movie as a file.

1. From the Projects browser, select the iMovie project you want to send, click the More button, then choose Share Project. If you’re editing a project, click the Share button. 
2. Click File.
3. Click the Resolution pop-up menu and choose a size for your video. The default resolution will be based on the content of your movie. Choosing a lower resolution will produce a smaller file that can be uploaded faster. Choosing a higher resolution will produce a larger file that’s great for viewing on a Mac or on a high-definition television (HDTV) using Apple TV.
4. Choose a location to save the video file, then click Save.
5. Drag the exported file into the Photos app to add the movie to your Photos library. If you have iCloud Photos enabled, you can access the video from all Apple devices signed in to the same iCloud account.

Share or export your iMovie project - Apple Support (IN)