At which point are ADE books tied to an account?

[Jellby]

When one buys Adobe DRM'ed books, when are they tied to a particular Adobe account (and associated devices)? If I get a link to an .acsm file, can I download it with any Adobe account (or with ADE on any computer), or is it already for a specific account? When I buy .epub books from a store, do I have to enter Adobe account info there or is it only important when I actually download the books?

The scenario is the following. I don't normally have a Windows computer, I don't have ADE installed, and I don't have an Adobe account. But I have access to someone else's computer with its ADE and Adobe account (and the corresponding adeptkey.der, if needed). I may want to buy some DRM'ed books, and I'd like to use my own credit card and everything, but use this someone else's ADE to download the books. Is it straightforward?

[wallcraft]

It is tied to an AdobeID when Windows Adobe Digital Editions (say) takes the .acsm file and downloads an .epub. The ebook stores don't know what AdobeID you are using. The only exceptions to this I am aware of are the Sony store, which requires you to use its own software for buying ebooks, and Foyes in the UK which won't download an ebook if ADE isn't present on your computer.