To ensure fair access to BLAST^® for all users, NCBI monitors BLAST usage from individual IP addresses and automatically places temporary restrictions on IPs with high usage. These restrictions include delaying searches and issuing warnings if an IP requests 100 or more concurrent searches.  

Will you be indefinitely penalized for heavy usage from your IP address?
No. These warnings and limits are transient. As searches from your IP clear the BLAST system, NCBI will remove the warnings and lift the limits.

Can you avoid being penalized?
Yes. You can introduce several strategies that we describe in the article on teaching BLAST in a classroom.