It is called a slot1 flashcart. It is what the majority of us are using right now. You might want to get either a M3 Real slot1 or a M3i Zero slot1 so you can continue using the MP as extra storage for some games.
After looking at what AAI:ME has, it is only 64MB and has a 512kb save file size, that excedes the game size of the MP can load by 32MB. Means you can no longer run games that are larger than 32MB (that is a limitation of GBA hardware).
Either way, it is time for you to upgrade or be limited to playing games that fit under 32MB or doesn't have Anti-Piracy code only.