Whether is grammatical or not depends on whether you’re talking about prescriptivist or descriptivist grammar. (this is an issue that is discussed a lot in introductory linguistics classes)
Prescriptivist: “This is the way you should talk. Infinitives should not be split, sentences should not end with prepositions, anymore should only be used in negative sentences …” That kind of thing. A lot of these rules were based on the grammatical rules of Latin, but I don’t know about the use of anymore.
Descriptivist: “In certain areas, the word anymore is used in affirmative sentences thusly: [insert appropriate examples here; this isn’t part of my dialect, so I dunno]. Also, speakers often split infinitives and sentences can sound very awkward when the speaker goes out of their way to avoid ending prepositions.”