In March 2016, Adobe will change the distribution of Enterprise Adobe Flash Player. If you want to use the Enterprise plugin after this deadline, you are required to apply for a license.
Older installations will continue to work in your Firefox profile. However, some sites that recommend downloading the player in Firefox (to enable you to see certain content) may or may not tell you to download it, since a distribution license is now required.
As an alternative – if you do not want to create an Adobe ID for a distribution license – you can try other versions of Flash Player from this Adobe site.
For detailed information, see the Adobe Flash Player FAQ page.