wii classic games question.

I bought a wii points card before I knew I needed to buy the wii classic controllers (or use camecube ones) to play the classic downloadable games. I plan to download Super Mario Brothers and Street Fighter, but a question occurred to me.

I know there is limited space on the Wii, so you can only download so much stuff (only have so many channels). If I later delete Street Fighter for example to grab something else and want it back down the road, do I have to pay for it again with more Wii points or does Nintendo keep track of what games I purchased and allow me to download it again without paying twice?

Just want to make sure I know what I'm getting into. At least with Steam for example, they know which games are already purchased and you can re-download them forever.