What can I do about arm lift scars? I'm a year post op. (photos)

Steroid injections and laser may help. Scar revision may be considered as well.An exam and consultation with a/your plastic surgeon is recommended to discuss your options and expectations.

Thank you very much for your question and your pictures. It looks like you have a scar that is both wide and red. It has already been over a year so it looks like it has had time to mature. With that said, you can try some of the available scar treatment modalities (if you haven't already done so), to see if this would improve over time. These modalities may involve some combination of taping, scar cream and massaging. 
You can also try steroid injection and/or laser to decrease the "redness" of the scar. These treatments will not make the scar go away, but will make it less "red," which generally makes the scar less "visible."
A scar revision is also an option and scar revisions generally improve the scar. I would recommend seeing your board-certified plastic surgeon to go over these options.