I suppose English might not be your native language, and that's fine, but it's been discussed in the thread already.
You need to launch the game in Origin's Offline Mode for the money cheat to work. Even then, however, once you go online again, the cloud servers will see a mismatch of earnings and inventory and revert your money back to what it was last. This is not avoidable.
You can still buy cars and parts offline with the money cheat, however. And those purchases will persist if you upload your local inventory when the game prompts you upon going back online.
So it works where it matters. Just play the game for a while, reopen it offline, cheat with money, buy the cars or parts you need, win one race, then save and quit. Then reopen the game online and your purchases should remain.
Just don't buy too many cars and hope to sell them, like I did - it turns out you can't sell cars. Just parts.
You can sell cars and parts. Sell cars by going over to the showroom tab, select a car and you'll have an option to sell it.
Oh man, thanks! Yeah, the showroom defaulted to the crew and I hadn't noticed it giving me t he option finally in my own garage. I guess this is going to be the best way to retain cash if you really need it (i.e. still progressing and need to buy just-unlocked upgrades).
The previous options from Payback were awesome, I can mention - really liked the ultra speed boost, jumping, etc. Quietly waiting to see how the CH crew handles this one before actually making requests, I'm happy enough at the moment.