Hi and Welcome to RG.

If you look after your A7750 movement it should last you as long as a ETA7750. You can always go the extra mile and if it dies have it replaced by a ETA Swiss 7750 movement, these are expensive but better quality. The key however is to have your watch well looked after, even with the swiss movements if you don't have them serviced regularly they will end up dying. These are mechanical parts that are subject to wear and tear and need lubrication and attention every so often.

Have a look around the forums, plenty of information available here as to movements and how to look after them, you can even start learning on how to service your own movements if you're into it. There's some very nice tutorials available in the forums that cover some common problems.

Enjoy the ride...