I was wondering if someone could help me...

1) how long is the trial version?
2) on some items in the supplies area, it says 'please register'. Does that mean I have to register with LDW or that I need to buy the game?

You didn't say which version of Fish Tycoon you're playing. The different versions use different trial modes, but all of them are restricted in some way - either a time limit or feature limitations.

When the game says "Please register" it means that you need to buy the game. Upon purchase, you will receive a registration code that will unlock the full game.

Keep in mind that registration codes for the Windows version are different for each site that sells the game. If you download a demo version from one site, but purchase the game from a different site, you'll need to download the game again from the site where you made the purchase in order to use your registration code.

alright, well it was trial 1.0 from here.

That could still be either the Pocket PC or the Windows version of the game, since they are both at v1.0!

windows sorry

That's what I assumed, which is why I included expanded advice about the Windows version!