If you use the “RIM Base Card Product Offer” described here in Section 1, then there is no cost. However, section 2 (f) says that if you want to use the "Enhanced map APIs", you will need to enter a license agreement with TANA. Most likely, if you have access to these APIs, then there should be a license in one or all files and, possibly, instructions attached to the API that describe in detail how to enter a license agreement with TANA.
Short answer: you can use the map APIs for free if you use the basic APIs. If you want to use the more advanced features presented in the "Advanced Map APIs", read the documentation related to these APIs. The API may have an implied license.