A dated copy of the official program page and FAQ as read at each decision point, the written sponsorship arrangement setting out who pays what, any official correspondence about the individual case, and the accountant's record of the fees and obligations relied on.
Keep the date, not just the number
Terms published on a government page can change, and a figure remembered without its date is unusable when someone asks what was relied upon. Viktor should keep a dated copy of the official material each time it informs a decision, so the file shows what the terms were when he acted rather than only what they are today.
Alongside it belongs the sponsorship arrangement in writing: who pays the US$15,000 processing fee per person, who bears the principal gift of US$2 million per corporate-sponsored employee, who carries the one percent annual maintenance, who pays the five percent transfer fee, and what happens if the relationship ends. Individual correspondence from official channels should be filed separately from general program material, because a notice about his case and a public page answer different questions and are not interchangeable.