There is no explicit limit to the number of recipes you can store in the app. Some of our users have well over 100,000 recipes.
The only constraint to the number of recipes you can store is the amount of free space you have on your device and the type of data you are storing with each recipe. If your recipes are mostly text-based and maybe contain a thumbnail, then each recipe will only consume a few kilobytes of space at most. On the other hand, if each of your recipes contains multiple, full-sized photos along with it, then each recipe may take up a few megabytes (depending on how many photos there are).