The offer ends at midnight BST on 19 June.
Different FMP sites have different names for the subscription - in the UK it's PRO, and I think the others (dot com, Australia, and Ireland) call it ULTIMATE. Same access to everything on the site (except 1921 census), including all but the most recent updates to the British Newspaper Archive.

Only available to new or lapsed subscribers.

Although the sub doesn't include the 1921 census, you do get 15% discount on entries you want to access.