If I use...

Probably yes.
Or at least till your guest pass runs out.

What datenshi said. About "staying forever", try force syncing your account.

Sync your account after the guest pass ends.

Nope, u cant. I activated my guest pass and now i cant enter RO giveaways.

I love how only Charlz actually read the thread and seemed to understand. Just in case he was also incapable of reading, given the changes Valve have made to the free weekends, chances are a guest pass will also block you out from giveaways here, even after it's ended. You can message Valve, I suppose, ask for its existence to be forcibly removed from your account.

You won't be able to enter giveaways until your guest pass ends. After that - just resync your account and you will be good to go!

you wont acually win, so ? .....