As I understand, promo-codes expire 4 weeks after generated. You are also given 50 codes per version uploaded.
But, what would happen if you generate a promo-code, e.g. for app version 1.0, then upload a new binary/version, e.g. app version 1.1, to iTunesConnect and give out more promo-codes?
Would the other promocodes expire immediately when the new version is ready or would they still be active until their 4-weeks are past? Also, would they then be able to download version 1.1 instead of 1.0 (on which they were generated) ?
You would get 50 new promo codes for your new version. All promo code are valid for 4 weeks, regardless of version.