How long to keep vote in your wallet - forever?
A vote goes through when you mint a block. You can check it out here: http://blockexplorer.nu and pop your minting address in.
I’d also like to know if there’s anyway you can tell from your wallet that your vote has been passed.
Hopefully someone here can offer some advice.
Not sure if I understand the question correctly, but your vote will be counted for 10,000 blocks, which corresponds to roughly one week.
You can see in the transactions tab when you minted a block. However, if you are using a data feed and your voting may change without notice then there is currently no wallet feature that easily allows you to analyze this. You may want to take a look into the RPC API which allows you do perform this analysis (but it involves scripting).
Maybe he wants to know when to remove it?
Answer would be: after it passed.
Keeps the blockchain small and tidy.