All prior FL Studio Betas have expired, you need to download the FL Studio 10 release candidate to continue projects started in earlier betas.
Official download link:
We are excited to announce that the FL Studio 10 is now available from our download partners here or from your account.
You can find it under the FL Studio Producer & FL Studio Fruity license sections until our hosting partners publish the installer.
This installation will not expire it is an official FL Studio 10 installer. Release candidate means that we intend to release this to the wider public if no problems are experienced with the installer.
Please try it and let us know how it behaves.