Securing substitute lead on abutments

[muteparade]

Hi, after having my roof abutments 'professionally' patched up a couple of times only to find bits of mortar raining down on my car I eventually bought the gear and went up there myself and covered them in a lead substitute. This has been great for a few years but it's now lifting badly at the gable end with the wind. I originally stuck them down with Ubiflex High Tack adhesive and some big bolt head screws, I'm now thinking I need to screw fix a strip of flat bar down the edge so it can't lift.
Any recommendations on what metal type (if metal at all) would be greatly appreciated. I had thought anodised Aluminium as galvanised steel will maybe eventually rust??
Note the pic is pre-lifting problem.
Also any ideas on a cheaper alternative to the Ubiflex high tack adhesive?
Cheers