The Pro payment is a one time payment & you can use whatever installers you download, while your benefits are current, til the cows come home.
But what they don't tell you is that you have to save whatever installers you download...because once your Pro expires you can't download installers for free any more. It's a bit sneaky & heaps of people get caught out, thinking that they can go on downloading Pro installers forever once they've paid.
Ultimately, it's up to the user to save & back up their Pro installers & I wish LW would make that a bit clearer in the Pro info

So if you ever buy Pro again, remember to save & back up those installers.
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The .exe icon is the installer, the icon with LW's version number is the shortcut to open LW
Is your brother using LW? If so, make sure that you're not using the same port number as he is. In LW tools > options > advanced > firewall will show you LW's listening port number. If yours & your brother's are the same...change yours to 65000 > apply > ok. Now restart LW & see if it connects.
Go to Start > Control Panel > Security Centre. Click on Firewall...that will show you which firewall is currently on. Make sure that firewall's allowing LW access:
User Cant Connect - LimeWire
Have you deleted that preferences folder (with LW properly closed)? You'll know if you've deleted it...once you restart LW, you'll go through the setup wizard all over again. If you don't have to go through the setup wizard, the folder hasn't been deleted properly & so you'll need to try again.
Go to the gnutella.net file & hover your mouse over the file...how big is it? If the file is 0 KB, you need to replace it again (should be ~20 KB).
If deleting prefs doesn't help & your gnutella.net file is ok, you could try port forwarding for your router. Your router has it's own firewall & maybe that's why you've seen the firewall icon. There aren't any instructions for your WRT54G v8 but try these for v5:
Port Forwarding for the Linksys WRT54Gv5
You'll need to set up a static IP address
first, there's a link within those instructions showing you how. LW's listening port, port in the 'manual port forward' box & port forwarded within your router's setup need to all be the same number.