Hi TiagoPina,
I recommend you look into a product called Passkey BD from DVDFab. It's a driver that makes BDs read as region-free to PowerDVD, so that the change of region doesn't trigger one of the limited number of region changes available in the software.
Blu-ray uses a different region code schema from DVD, which is why they changed the system from region numbers to letters. With DVD, the region is locked into your optical drive, and requires the firmware to be hacked to free up the limitations. With Blu-ray, it's done in the software, so it's PowerDVD that contains the limit on the number of times you can change the region; Passkey simply intercepts the region information from the disc and prevents it from reaching PowerDVD.
It's not a piracy tool; I'm not into piracy at all, and all my discs (and PowerDVD) were bought fair and square. And the situation isn't Cyberlink's fault; as I understand it, the 5-changes limitation is part of the terms of licensing the Blu-ray format. But it's perfectly legal to buy BDs from multiple regions, and to buy multi-region BD players, so I don't see why the software should be any different when it doesn't involve piracy. I realise that idea is not going to be endorsed by Cyberlink, but then it's not breaking any of the PowerDVD Ts&Cs, either.
Anyway, it may be a solution to your situation.