Q: How can I get iMovie on my old MacBook Air 2008

Hey!
A couple days ago I bought a used MacBook Air 2008. The price was good, and it works just fine, except for one little issue: I cannot install iMovie, which I really need. I cannot install it from AppStore since the latest OC my MacBook can run is Lion OC X 10.7.5. as well as didn't get the disk with all the iLife apps
I wonder if there is any other way I can get it on my Mac, since I need it a lot.

If you have any ideas, please share. I'd appreciate any help!

Thank you in advance