From Longman Dictionary of Contemporary Englishcount somebody in phrasal verbINCLUDEto include someone in an activity When the game gets started, you can count me in. → count→ See Verb table
Examples from the Corpus
count in• That is why a third principle will also count for a lot in 1991.• A half-revolution would be lost for every record, just to update the count field.• Chapters 2 and 3 are designed to help you on both counts.• The party believes it looks promising on both counts.• Developers who are counting on putting in a huge residential development are fighting the plan.• This is often true even if she accurately counts the elements in each row.• Novacek is the man Aikman counts on in short-yardage situations and close to the goal line.• We are too impertinent with the past, counting on it in this way for a reliable frisson. 