Finally found a solution for this problem, this is the easy and short solution . The long one is to compile by myself and although is working admob don’t work so I stick to the short solution.
Basically you have to decompile the apk, modify, compile again and sign. The problem is singing, because we don’t have the private key, but it is all explained on the PDF.
On this link there is the PDF and some of the needed files.
drive.google.com/open?id=1Fp9BS … iSacnJKG3F