Trial apps, keys, future re installation?

[Macbobit]

Hi I'd like to buy some keys for some trial software I have downloaded and really like.

I'm a bit worried that down the line if I have to reinstall any of the programs for any reason that i won't have access to installation disk like I would if I bought the package in a box from a store or online.

How do most people eliminate this concern?

I'm specifically interested in using Aperture 2, and don't want to go through all the effort of reinstalling the program with new version from the store.

 

[maflynn]

Many trial apps are the full application that only require the license key (and w/o the key you get 30 days of free usage, i.e., a trial period). So it doesn't matter if you don't have the media down the road just as long as you have the license key.

I've never gone to a store to get software [re]installed